Name: single phase transformer testing
Uploaded: 2023-04-30T06:42:08.000Z
Duration: 10 min 50 s
Channel: JoVE

K12 Standards

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

High School

Physics

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

P-PS2-6.

Single Phase Transformers

1. 直流测试
<ol>
	<li>打开实验台上可用的低压直流电源。</li>
	<li>将其电压输出设为 0 V，并将电流限值设为 0.8 A。</li>
	<li>仔细检查电路连接，然后将电源输出端连接到初级绕组（IN1 和 IN2）两端。次级绕组（OUT1 和 OUT2）保持开路。</li>
	<li>开启电源，并略微增加电压，直到达到电流限值。注意：电源在开启时可能已处于电流限制状态。请勿提高电流限值。</li>
	<li>记录电源显示屏上的电压和电流读数。</li>
	<li>将电压调回 0 V，然后断开电源连接。</li>
	<li>将电流限值调整为 4 A，然后将电源输出端连接到次级绕组（OUT1 和 OUT2）两端。初级绕组（IN1 和 IN2）保持开路。</li>
	<li>开启电源，并略微增加电压，直到达到电流限值。注意：电源在开启时可能已处于电流限制状态。请勿提高电流限值。</li>
	<li>记录电源显示屏上的电压和电流读数。对于该变压器，输入电压为 3.5 V，电流为 0.8 A。</li>
	<li>将电压调回 0 V，关闭电源，并断开连接。</li>
	<li>使用万用表测量初级绕组两端的电阻。</li>
	<li>使用万用表测量次级绕组两端的电阻。</li>
	<li>通常情况下，由于理想状态下两侧功率相等，高电压侧的电阻会高于低电压侧的电阻；电压越高，电流越小，因此电阻越大。直流测试结果与万用表测得的电阻值应非常接近。</li>
</ol>
2. 开路测试
<ol>
	<li>确保三相电源已关闭。</li>
	<li>连接开路试验电路（图 1）。使用数字功率计。</li>
	<li>确保可变变压器（VARIAC）处于 0% 位置。</li>
	<li>仔细检查电路连接是否与图 1 所示一致，然后打开三相电源。</li>
	<li>缓慢调节可变变压器（VARIAC）旋钮，直至数字功率计上的电压读数达到 24 V。</li>
	<li>记录功率计的电压、电流、有功功率和功率因数。</li>
	<li>将可变变压器（VARIAC）调回 0%，关闭三相电源，并断开可变变压器输出端。</li>
	<li>在开路或空载试验中，励磁电抗（Xm）和铁损电阻（RC）可根据电流（IOC）、电压（VOC）和功率（POC）的测量值按以下公式求得： 
	RC= VOC2/POC （1） 
	和 Xm= VOC2/QOC （2） 
	其中 QOC2=(VOCIOC)2 - POC2 （3）</li>
</ol>
<img alt="三相电路图，包含可变变压器，展示输出连接和电缆布局。" src="/files/ftp_upload/10151/10151fig1.jpg" data-altupdatedat="1761830439000" data-alt="图 1"> 
图 1：直流测试示意图。<a href="//cloudfront.jove.com/files/ftp_upload/10151/10151fig1large.jpg" target="_blank">请点击此处查看此图的放大版本。</a>
3. 短路测试
<ol>
	<li>确保三相电源已关闭。</li>
	<li>连接短路试验电路（图2）。确保IN1和IN2连接至调压器（VARIAC）输出端。</li>
	<li>确保调压器（VARIAC）处于0%位置。</li>
	<li>计算变压器的额定输入电流。该值可通过输入侧的伏安（VA）额定值除以电压额定值得到。例如，若输入电压为115 V，VA额定值为100 VA，则输入电流额定值为100/115 = 0.87 A。</li>
	<li>检查电路连接无误后，开启三相电源。</li>
	<li>缓慢而谨慎地调节调压器（VARIAC）旋钮，直至数字功率计上的电流读数达到额定输入电流。</li>
	<li>记录功率计上的电压、电流、有功功率和功率因数。</li>
	<li>将调压器（VARIAC）调回0%，关闭断路开关，并断开调压器（VARIAC）输出端。保持调压器（VARIAC）的三相电缆连接。</li>
	<li>移除变压器次级绕组两端所接的短路装置。</li>
	<li>在短路试验中，通过测得的电流（ISC）、电压（VSC）和功率（PSC）可求得两个绕组的漏电抗（X1+X2'=Xeq）和导线电阻（R1+R2'=Req），计算公式如下： 
	Req=PSC/ISC2 （4） 
	和 Xeq= QSC/ISC2 （5） 
	其中 QSC2=(VSC ISC)2 - PSC2 （6）</li>
	<li>通常假设X1等于X2'；而R1和R2'可采用直流试验所得数值（或至少已知其中之一）。若未进行直流试验，通常可假设R1与R2'相等。</li>
</ol>
<img alt="三相短路测试示意图，包含可变变压器、变压器和五线电缆装置。" src="/files/ftp_upload/10151/10151fig2.jpg" data-altupdatedat="1761830439000" data-alt="图2"> 
图2：短路测试示意图。 <a href="//cloudfront.jove.com/files/ftp_upload/10151/10151fig2large.jpg" target="_blank">请点击此处查看此图的放大版本。</a>
4. 加载测试
负载测试显示了变压器输入侧与输出侧之间的电流和电压值的相关性，理想情况下， V1/V2 = I2/I1 = N1/N2 = a，其中N表示线圈匝数，下标1和2分别表示初级侧和次级侧，a为匝数比。次级侧的阻抗折算到初级侧为R'=a2R或X'=a2X。
<ol>
	<li>确保三相电源已关闭。</li>
	<li>连接负载测试电路（图 3）。确保 IN1 和 IN2 已连接至 VARIAC 输出端。</li>
	<li>确保 VARIAC 处于 0% 位置。</li>
	<li>将示波器差分电压探头跨接在初级侧，设置为 1/200。使用适当的缩放系数调整探头测量值，使偏置电压为 0 V。</li>
	<li>连接示波器电流探头以测量负载电流。将探头测量值调整为 0 mV 偏置，缩放系数设为 1X，对应 100 mV/A 的设置。</li>
	<li>检查电路连接无误后，合上三相隔离开关。</li>
	<li>缓慢调节 VARIAC 旋钮，直至 VP 读数为 115 V。</li>
	<li>记录两个数字功率计的电压、电流、有功功率和功率因数。</li>
	<li>捕获示波器屏幕图像，至少显示三个完整周期。</li>
	<li>关闭三相电源，并将 VARIAC 调回 0%。</li>
	<li>将单个 100 Ω 电阻替换为三个并联的 100 Ω 电阻。</li>
	<li>开启三相电源，缓慢调节 VARIAC 旋钮，直至 VP 读数为 115 V。</li>
	<li>仅记录两个数字功率计的读数（无需捕获示波器屏幕图像）。</li>
	<li>将 VARIAC 调回 0%，断开隔离开关，并拆除实验装置。</li>
</ol>
<img alt="三相变压器示意图；VARIAC 接线、电压和电流测量；电路符号。" src="/files/ftp_upload/10151/10151fig3.jpg" data-altupdatedat="1761830439000" data-alt="图 3"> 
图 3：负载测试电路示意图。 <a href="//cloudfront.jove.com/files/ftp_upload/10151/10151fig3large.jpg" target="_blank">请点击此处查看此图的放大版本。</a>

所述测试对于评估变压器的阻抗并确定其等效电路参数至关重要。由于变压器的应用范围从简单的充电器到大功率交流输电系统不等，因此针对不同应用对各类变压器进行恰当表征显得尤为必要。在电力系统中，变压器阻抗可用于确定变压器两侧可能出现的故障阻抗，估算变压器的效率，计算其线路和负载调整率，并在模拟较大规模电气系统时将变压器作为其中一部分进行建模。

单相变压器

来源：Ali Bazzi，康涅狄格大学电气工程系，斯托尔斯，康涅狄格州。
变压器是一种静止的电气设备，用于升高或降低交流电压。它们通常由初级和次级线圈（或绕组）构成，初级侧的电压在次级侧被升高或降低，反之亦然。当电压施加到其中一个绕组上并产生电流时，磁芯中会感应出磁通，从而耦合两个绕组。当通入交流电流时，将感应出交变磁通，其变化率会在次级绕组中感应出电压（法拉第定律）。两个绕组之间的磁通耦合程度取决于各自绕组的匝数；因此，如果初级绕组的匝数多于次级绕组，则初级侧的电压将高于次级侧，反之亦然。
本实验通过测定单相变压器的等效电路参数，对其特性进行表征。实验包括三项测试：开路测试、短路测试和直流测试。

通过进行直流、开路、短路和负载试验，确定了变压器的等效电路参数；因此，可以对变压器的实际运行行为进行仿真、操作和分析。
短路试验通常通过在高压侧施加逐渐增加的电压来进行，因为高压侧只需施加较小的电压，即可在被短路的低压侧产生额定电流。该方法有助于使变压器在额定电流下运行，从而测试其载流能力。
本测试中，短路电压为 11.9 V，短路电流为 0.865 A，短路功率为 7.11 W。利用短路测量值可计算漏电抗，本例中为 9.94Ω。由此得到的一次侧电抗和折算后的二次侧电抗均为 4.97Ω。总导线电阻计算为 9.502Ω。减去一次绕组的电阻（4.375Ω）后，得到 5.127
至于开路试验，它有助于确保变压器在运行额定电压时满足电压绝缘能力的要求。其他试验，如用于绝缘材料击穿的高电位绝缘试验、机械振动试验等，也会进行，但主要用于更高级的应用场合。
对于该变压器，开路电压为 23.8 V，开路电流为 335.5 mA，开路...

来源：Ali Bazzi，康涅狄格大学电气工程系，美国康涅狄格州斯托尔斯市。  
变压器是一种静止的电气设备，用于升高……

单相变压器用于电源和其他设备中，以将交流电压和电流从一个值转换为另一个值。变压器对于提供电气隔离至关重要，而电气隔离是许多实验室仪器和医疗设备安全运行所必需的。如果输入端和输出端不共用一个公共端子，则变压器可以在完全物理分离的情况下传输电能。这可以防止系统危险高压侧的电流传递到安全低压侧的电路和人员。了解变压器内部的各个组件对于变压器的分析与设计具有重要意义。本视频将演示如何通过执行各种测试来测量变压器组件的电气参数。变压器具有一对与初级绕组或线圈相连的输入端子，以及一对与次级绕组相连的输出端子。一个由钢、铁氧体甚至仅为空气构成的铁芯在磁学上耦合这两个绕组。当一个绕组两端施加电压时，电流流经该绕组，从而产生磁场。磁通量（即穿过某一面积的磁场总量）通过铁芯耦合到次级绕组，并在其中感应出电压。这一原理称为互感。法拉第定律指出，磁通量变化率乘以绕组匝数等于感应电压，该电压也称为电动势（EMF）。若在初级绕组两端施加直流电压，由于其值恒定，所产生的磁通量也保持恒定，变化率为零，因此不会感应出电压。然而，交流电压会产生变化率不为零的磁通量，从而在次级绕组中感应出电压。换句话说，变压器的正常工作必须依赖交流电压。变压器的匝数比定义为初级绕组的匝数除以次级绕组的匝数。初级电压与次级电压之比等于匝数比。根据匝数比的不同，变压器可以升压、降压或保持电压不变。初级电流与次级电流之比等于匝数比的倒数。例如，若初级线圈有3匝，次级线圈有30匝，则匝数比为0.1。此时，初级侧120伏的电压将在次级侧产生1200伏的电压；初级侧10安的电流在次级侧将变为1安。最后，若次级线圈接有阻抗为Z2的负载，则初级线圈将呈现一个表观负载或反射负载Z2′。该反射负载的数值等于次级侧阻抗乘以匝数比的平方。理想情况下，变压器可被视为一对耦合电感器，能够无能量损耗地将能量从一个线圈传递到另一个线圈。然而，实际变压器存在漏磁通或漏感，这部分磁通不参与绕组间的能量传递。此外，实际变压器还会因绕组电阻而产生功率损耗和发热。铁芯中感应的磁通量还会因铁损电阻而成为额外的热源。为避免损坏，通常规定最大输入功率，称为视在功率额定值（VA额定值），即输入电压与电流的乘积。在介绍了变压器的基本原理之后，接下来我们将探讨如何测量变压器的电气参数。本实验所用变压器的初级绕组最大可承受 115 伏电压，次级绕组最大可承受 24 伏电压。此外，该变压器的额定功率为 100VA，表示其可接受的最大功率为 100 瓦。本直流测试用于测量每个绕组的电阻，以用于变压器的等效电路模型。首先将低压直流电源的电压输出设为 0 伏，电流限制设为 0.8 安培，然后关闭电源。将电源输出端连接至初级绕组，次级绕组不连接任何设备。打开直流电源，逐步增加电压，直至达到电流限制。记录电源显示屏上的电压和电流读数。通过将电压除以电流，计算初级绕组的电阻。将电源电压调回 0 伏并关闭电源。将电源输出端连接至次级绕组，初级绕组保持开路。将电源的电流限制设为 4 安培，然后逐步增加电压，直至达到电流限制。记录电源显示屏上的电压和电流读数。计算次级绕组的电阻。将电源电压调回 0 伏，关闭电源，并从变压器上断开连接。最后使用万用表测量初级和次级绕组的电阻，以验证计算所得的电阻值。开路试验用于测量互感电抗或铁心损耗电阻对电流变化的阻碍作用。铁心损耗电阻是等效电路中表征功率损耗的参数，用于近似变压器铁心中的功率损耗。在三相电源关闭且调压器（Variac）设定为0%的情况下，按图示连接电路。然后使用数字功率计测量变压器原边的开路电流和电压。开启三相电源，缓慢调节调压器的控制旋钮以升高电压，直至数字功率计显示为24伏。记录此时的开路电压、开路电流、开路有功功率及功率因数。利用这些数值计算变压器的等效电路参数。铁心损耗电阻RC由开路电压和开路功率计算得出。互感电抗XM则类似地通过开路电压、功率和电流计算获得。短路试验用于测量漏抗，也可确定两个绕组的导线电阻。首先，通过将变压器的伏安额定值除以输入侧的电压额定值，计算其额定输入电流。在电源关闭且可变变压器（Variac）输出调至零的情况下，按照图示连接电路。此次使用数字功率计测量短路电流和电压。开启三相电源，缓慢调节可变变压器以逐步升高电压，直至数字功率计上的电流读数达到额定输入电流。记录此时的短路电压和电流，以及短路状态下的有功功率和功率因数。漏抗等于初级侧电抗与反射至初级的次级侧电抗之和，通常假设二者相等。利用短路试验的测量数据计算漏抗。最后，通过将初级绕组的电阻与反射至初级的次级绕组电阻相加，计算两个绕组的总导线电阻。变压器是一种非常有用的电气设备，广泛应用于电能转换和为安全起见的电气隔离领域。负载测试用于测量初级侧电压与次级侧电压之比，以及初级侧电流与次级侧电流之比。实验电路在次级侧连接了一个100欧姆的电阻，并在两侧测量了电流和电压。当初级侧电压为115伏时，测量了两侧的电压、电流、有功功率和功率因数。初级电压与次级电压之比理论上应等于匝数比。一项针对小鼠嗅觉感觉神经元的研究使用氙闪光灯管发出的紫外光来解离特定化合物。驱动闪光灯管的电路需要通过升压变压器产生的高电压。与所有高压设备一样，安全设计中采用变压器实现电气隔离，以防止带有危险电压的元件与其他电路电子器件之间发生意外短路。您刚刚观看了 JoVE 关于单相变压器的介绍。您现在应该理解变压器的工作原理以及如何测量其等效电路参数。感谢观看！

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Electrical Engineering

电气工程

single phase transformer testing

Single-phase transformers step up or step down AC voltage in electric power systems. They are stationary electric machines with primary and secondary coils, also called windings. The primary winding receives the applied voltage, and the secondary winding delivers the changed voltage.

Inside the transformer, current in one winding creates magnetic flux in the core. This flux links the two windings and transfers energy between them. With AC current, the changing flux induces voltage in the secondary winding by Faraday's law. The voltage change depends on the number of turns in each winding. If the primary has more turns than the secondary, the primary voltage is higher. If the secondary has more turns, the secondary voltage is higher.

This experiment characterizes a single-phase transformer by finding its equivalent circuit parameters. It uses three tests: the open-circuit test, the short-circuit test, and the DC test. These measurements help describe how the transformer behaves under different conditions.

Single Phase Transformer Testing

electrical safety precautions and basic equipment

electrical-safety-precautions-and-basic-equipment

Safe Handling of High-Voltage Lab Power

Safe handling of high-voltage lab power is essential in electric machine and power electronics experiments. These labs involve electrical currents, voltages, power, and energy that require extreme care. The systems used in this work can include three-phase AC voltage at 208 V, 230 V, or 480 V. They may also use up to 250 V DC and currents that can reach 10 A. These levels can be dangerous if handled without proper attention. Electrocution can happen when electricity passes through the body.

characterization of magnetic components

B-H Curves and Inductor Core Limits

Magnetic components such as inductors and transformers depend on the core material around their windings. In this experiment, students get hands-on experience with these parts from both a design view and a material view. The work focuses on B-H curves, which show the magnetic behavior of a material. A B-H curve describes the magnetic flux density the core can support as current flows through the windings. It also helps show the limit before magnetic saturation occurs. Magnetic saturation...

introduction to the power pole board

Power Pole Board for DC/DC Converter Labs

The HiRel Power Pole Board is a flexible tool for studying DC/DC converters. A DC/DC converter changes direct-current voltage and current from one level to another. In many cases, voltage conversion is the main goal. This board supports several converter types on one platform. It can be used to examine boost converters, which step voltage up, and buck converters, which step voltage down. It also helps students study buck-boost converters, which can step voltage up or down. The board is also...

dc/dc boost converter

Stepping Up DC Voltage with Boost Converters

DC voltage can be increased with a boost converter. This step-up circuit is useful in many applications where a DC source must be raised without first converting it to AC, using a transformer, and then rectifying the transformer output. A boost converter uses an inductor as an energy storage device. The inductor supports the output with extra energy in addition to the DC input source. That added energy raises the output voltage. This experiment studies several characteristics of a boost...

dc/dc buck converter

Buck Converter Step-Down DC Voltage

A DC/DC buck converter steps down DC voltage in an efficient, regulated way. Unlike transformers, which easily raise or lower AC voltage and current, DC systems need switching power converters to change voltage levels. The buck converter works by chopping the input DC voltage with a series input switch. An L-C low-pass filter then smooths the chopped signal and extracts the average output voltage. A diode gives the inductor current a path when the switch is off during part of the switching...

flyback converter

Flyback Converter Voltage Step-Up and Step-Down

A flyback converter is a buck-boost converter that can both step voltage up and step it down. It also provides electrical isolation between the input and the output by using a coupled inductor, or flyback transformer. The coupled inductor acts like a transformer with a turns ratio, but it also stores energy through the air gap. This setup gives the converter both voltage step-up and step-down capability. In the experiment, the converter is studied in open-loop operation with a manually set...

single phase transformers

Single-phase transformers step up or step down AC voltage in electric power systems. They are stationary electric machines with primary and secondary coils, also called windings. The primary winding receives the applied voltage, and the secondary winding delivers the changed voltage. Inside the transformer, current in one winding creates magnetic flux in the core. This flux links the two windings and transfers energy between them. With AC current, the changing flux induces voltage in the...

single phase rectifiers

AC to DC Conversion with Rectifiers

Rectifiers convert AC power into DC power for electronic circuits. A DC power supply provides unidirectional voltage and current. Batteries can do this, but they are limited by lifetime and cost. Using a rectifier is another way to turn AC line power into DC power. A rectifier is a device that lets current pass in one direction and blocks it in the other. It works after a forward voltage threshold is reached. Rectifiers may use a diode, a silicon controlled rectifier, or other silicon P-N...

thyristor rectifier

Controlling SCR Half-Wave Rectification

Thyristors, also called silicon controlled rectifiers (SCRs), are used to control current in a rectifier circuit. Like diodes, they let current pass from the anode to the cathode and block current in the opposite direction. Unlike a diode, a thyristor can be turned on with a gate terminal that receives a small current pulse. A thyristor is a four-layer device with alternating n-type and p-type layers. These layers form a PNPN structure with three junctions. The device has three terminals. The...

single phase inverter

DC to AC Conversion with Half-Bridge Inverters

DC to AC conversion is the main idea behind a power inverter. DC power flows in one direction, while AC current changes direction at about 50-60 Hz. Many electronic devices are designed to run on AC power, so a DC source must be inverted before it can be used with them. An inverter makes this change through switching action. The switches repeatedly flip the polarity of the input DC source at the output, or load side, for part of a switching period. A typical power inverter needs a stable DC...

dc motors

DC Motors and Generator Action

DC machines use direct current and direct voltage to create motion or generate electricity. They were the first machines of this kind to be invented. A DC machine works with two magnetic fields that are controlled by DC currents, and the same machine can be set up as either a motor or a generator when the right field excitation is available. In a DC machine, the field is usually on the stator side and the armature is on the rotor side. That arrangement is the reverse of what is found in many...

ac induction motor characterization

Three-Phase Motor Equivalent Circuit Tests

Three-phase induction motor testing can be used to find equivalent circuit parameters. The experiment uses the per-phase equivalent circuit to model the motor. This model keeps the important behavior of the original system and makes calculations easier. The procedure uses tests similar to those used in transformer characterization. These measurements help estimate the motor's circuit values from its electrical response. The experiment also aims to operate the motor in the linear torque-speed...

vfd-fed ac induction machine

Variable Frequency Drive Speed Control

Variable frequency drives, or VFDs, control the speed of AC induction motors. They are a type of adjustable speed drive and are becoming standard equipment for powering most AC induction motors. In industrial and automation settings, VFDs can provide strong control of motor speed, torque, or position. This experiment focuses on speed control with open-loop operation. It uses constant voltage-to-frequency ratio control, also called V/f control. The motor usually operates at a rated stator flux,...

ac synchronous machine synchronization

Grid Connection of AC Synchronous Generators

AC synchronous generators are a major source of electrical power worldwide. They are three-phase, wound-rotor machines that are used in many power plants. These generators need a prime mover and an exciter to produce power. A prime mover is the device that spins the generator, often a turbine driven by fluid. That fluid can come from water flowing from a dam through a long nozzle or from steam made by burning coal. Most power plants use synchronous generators, including coal, nuclear, natural...

ac synchronous machine characterization

Three-Phase Synchronous Motor Starting and V-Curves

Three-phase synchronous motors and generators are important AC machines. Wound-rotor synchronous motors are less common than permanent magnet rotor synchronous motors because the rotor field uses brushes. Synchronous generators are much more common. They are used in most existing power plants because they provide excellent frequency and voltage regulation. A synchronous motor runs at the same speed as the stator magnetic field. This gives it almost 0% speed regulation, so the rotor speed stays...

electrical engineering

本系列从电气安全视频开始, 介绍了电气实验室中常用设备的最佳实践。随后的视频介绍了电感器、变压器、变流器、整流器和逆变器等元素。

Learn how a single-phase transformer works and how open-circuit, short-circuit, and DC tests are used to find its equivalent circuit parameters.

Single Phase Transformer Testing | JoVE K12

Ali Bazzi

Overview

Principles of Single-phase Transformers

DC Test for Winding Resistance

Open Circuit Test

Short Circuit Test

Applications

Summary

Newton's Second Law

Newton&#39;s second law is closely related to his first law of motion. It mathematically gives the cause-and-effect relationship between force and changes ...

Second Law: Motion under Same Force

Newton&#39;s laws can be applied to bodies at rest and bodies in motion. Newton&#39;s first law is applied to bodies in equilibrium, whereas the second ...

Force and Acceleration

Source: Nicholas Timmons,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of California, Irvine, ...

second-law-motion-under-same-acceleration

Second Law: Motion under Same Acceleration

Newton&#39;s second law of motion applies to bodies moving under the same acceleration. For example, when a baggage tractor pulls luggage carts, each cart ...

Newton's Laws of Motion

Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA
This experiment examines at various situations involving two interacting ...

Newton's Law of Motion

When we observe objects around us, one question that comes to mind is why they move or stay still. The answer to this question can be explained using ...

Analyze data to support the claim that Newton's second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.

P-PS2-1

Force and Momentum

Force and momentum are intimately related. Force acting over time can change momentum, and Newton&#39;s second law of motion can be stated in its most ...

Internal and External Forces

Newton&#39;s first law states that a net external force causes a change in motion. External forces act on an object or system, originating outside of the ...

Conservation of Momentum: Introduction

The total momentum of a system consisting of N interacting objects is constant in time or is conserved. A system must meet two requirements for its ...

Force

Forces affect every moment of our life. Our bodies are held to the Earth by force, and they are held together by the forces of charged particles. When we ...

Conservation of Momentum

Conservation of Momentum: Problem Solving

Solving problems using the conservation of momentum requires four basic steps:

	Identify a closed system, where the total mass is constant, and no net ...

conservation-of-linear-momentum-for-a-system-of-particles

Conservation of Linear Momentum for a System of Particles

In a game of billiards, when the cue ball strikes a stationary ball, it transfers some of its momentum to the stationary ball. The cue ball slows down, ...

principle-of-linear-impulse-and-momentum-for-a-system-of-particles

Principle of Linear Impulse and Momentum for a System of Particles

Consider a system of particles moving relative to an inertial frame of reference.
The equation of motion for such a system can be written as the sum of ...

Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.

P-PS2-2

principle-of-linear-impulse-and-momentum-for-a-single-particle

Principle of Linear Impulse and Momentum for a Single Particle

Linear momentum is a fundamental concept in physics that describes the motion of an object. It is a vector quantity, having a magnitude equal to the ...

principle-of-angular-impulse-and-momentum-problem-solving

Principle of Angular Impulse and Momentum: Problem Solving

Consider a ball of mass m, attached to a massless rod of known length, subjected to a time-dependent torque. If the initial velocity of the mass is known, ...

Linear Momentum

The term momentum is used in various ways in everyday language, most of which are consistent with the precise scientific definition. Generally, momentum ...

principle-of-angular-impulse-and-momentum

Principle of Angular Impulse and Momentum

The angular impulse and momentum principle provides insights into how forces applied at a distance from an object&#39;s rotational axis influence its ...

principle-linear-impulse-momentum-for-single-particle-problem

Principle of Linear Impulse and Momentum for a Single Particle: Problem Solving

Consider a massless pulley system consisting of a wooden box and a cylinder of known masses. Determine the speed of the attached objects at a specific ...

Angular Momentum

Angular momentum describes the rotational motion of an object.
It is defined as the moment of the object&#39;s linear momentum about a specific point O.
...

relation-between-moment-of-a-force-and-angular-momentum

Relation Between Moment of a Force and Angular Momentum

In a spinning top, applying a force at a distance from the center creates torque, which changes the angular momentum of the top, causing it to spin.
The ...

Apply scientific and engineering ideas to design, evaluate, and refine a device that minimizes the effect of a force on a macroscopic object during a collision.

P-PS2-3

Gravitation

In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down the ...

/files/media/science-education/science-education-thumbs/14716.jpg

Newton's Law of Gravitation

Our everyday observation tells us that all objects close to the Earth naturally tend to fall to the ground. Early philosophers assumed that this downward ...

gravitation-between-spherically-symmetric-masses

Gravitation Between Spherically Symmetric Masses

The gravitational potential energy between two spherically symmetric bodies can be calculated from the masses and the distance between the bodies, ...

/files/media/science-education/science-education-thumbs/14717.jpg

Gravity between Spherical Bodies

Newton&#39;s law of gravitation describes the gravitational force between any two point masses. However, for extended spherical objects like the Earth, ...

Coulomb's Law

Experiments with electric charges have shown that if two objects each have an electric charge, they exert an electric force on each other. The magnitude ...

comparison-between-electrical-and-gravitational-forces

Comparison Between Electrical And Gravitational Forces

There are four fundamental forces in nature: the gravitational force, the electromagnetic force, the strong nuclear force, and the weak nuclear force. To ...

Newton's Law of Gravitational Attraction

Sir Isaac Newton established the universality of the law of gravitational attraction based on empirical evidence and inductive reasoning. He published his ...

Newton's Law of Universal Gravitation

Source: Ketron Mitchell-Wynne, PhD,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of ...

Use mathematical representations of Newton's law of gravitation and Coulomb's law to describe and predict the gravitational and electrostatic forces between objects.

P-PS2-4

Types of Forces

In most situations, forces can be grouped into two categories: contact forces and field forces.&#160; Contact forces occur as a result of direct physical ...

Magnetic Fields

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Magnetic fields can be ...

Electric Charge in a Magnetic Field

Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA
This experiment duplicates J.J. Thomson's famous experiment at the end of ...

Electric Fields

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
An electric field is generated ...

Electromagnetic Fields

Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by ...

Magnetic Field Due to Two Straight Wires

Consider two parallel straight wires carrying a current of 10 A and 20 A in the same direction and separated by a distance of 20 cm. Calculate the ...

Energy Carried By Electromagnetic Waves

Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun&#39;s ...

Energy Stored in Capacitors

A parallel plate capacitor connected to a battery develops a potential difference across its plates.
By integrating the equation relating voltage and ...

Power and Energy

Energy is the total work required to drive the current through the circuit.
A rise in voltage results in more work done, passing more current, resulting ...

Voltage

The movement of electrons in a conductor requires some form of energy or work, usually provided by an external force, like a battery. This force is called ...

Electromotive Force

Electromotive force (emf) is the force that causes current to flow from a higher to a lower&#160; potential. The term &#34;electromotive ...

Electrical Energy

Using electric appliances for a longer period of time consumes more electrical energy and results in a higher electric bill. The energy produced by the ...

Electrical Current

Electrical current is defined as the rate at which charge flows. When there is a large current present, such as that used to run a refrigerator, a large ...

Electric Potential Energy

When an electric field accelerates a free positive charge q, it is given kinetic energy. The process is analogous to an object accelerated by a ...

Electrical Power

Electric power is the product of current and voltage, represented in units of joules per second, or watts. For example, cars often have one or more ...

Plan and conduct an investigation to provide evidence that an electric current can produce a magnetic field and that a changing magnetic field can produce an electric current.

P-PS2-5

sources-and-properties-of-electric-charge

Sources and Properties of Electric Charge

All objects we see around us consist of atoms, which combine to form molecules. The lightest element in the universe is hydrogen, and a hydrogen atom ...

Electric Charges

From lightning during thunderstorms to electronic devices, the phenomenon of electromagnetism is all around us. The electromagnetic force is one of the ...

Electron Behavior

Electrons are negatively charged subatomic particles attracted to and orbit around the positively-charged nucleus of an atom. They reside in spaces ...

Electronic Structure of Atoms


An atom comprises protons and neutrons, which are contained inside the dense, central&#160;core called the nucleus, with electrons present around the ...

Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.

Single Phase Transformer Testing

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