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Magnetism and induction exercises · Physics Playground

ExercisesPhysics

Magnetism and induction

25 problems with worked solutions, from Physics and College Physics.

Start with a random one

Learn it first: Magnets & Magnetic Forces, Electromagnetic Induction

Physics20.1 Magnetic Fields, Field Lines, and Force

ExampleTrajectory of Electron in Magnetic FieldA proton enters a region of constant magnetic field, as shown in Figure 20.20. The magnetic field is coming out of the page. If the electron is moving at 3.0× 10^6 m/s and the magnetic field strength is 2.0 T, what…With a figure
ExampleWire with Current in Magnetic FieldNow suppose we run a wire through the uniform magnetic field from the previous example, as shown. If the wire carries a current of 1.5 A in the y ^ -direction, and the region with magnetic field is 4.0 cm long, what…With a figure

Physics20.3 Electromagnetic Induction

ExampleEMF Induced in Conducing Coil by Moving MagnetImagine a magnetic field goes through a coil in the direction indicated in Figure 20.37. The coil diameter is 2.0 cm. If the magnetic field goes from 0.020 to 0.010 T in 34 s, what is the direction and magnitude of…With a figure
ExampleMagnetic Induction due to Changing Circuit SizeThe circuit shown in Figure 20.38 consists of a U-shaped wire with a resistor and with the ends connected by a sliding conducting rod. The magnetic field filling the area enclosed by the circuit is constant at 0.01…With a figure

College Physics22.4 Magnetic Field Strength: Force on a Moving Charge in a Magnetic Field

Example 22.1Calculating Magnetic Force: Earth’s Magnetic Field on a Charged Glass RodWith the exception of compasses, you seldom see or personally experience forces due to the Earth’s small magnetic field. To illustrate this, suppose that in a physics lab you rub a glass rod with silk, placing a…With a figure

College Physics22.5 Force on a Moving Charge in a Magnetic Field: Examples and Applications

Example 22.2Calculating the Curvature of the Path of an Electron Moving in a Magnetic Field: A Magnet on a TV ScreenA magnet brought near an old-fashioned TV screen such as in Figure 22.21 (TV sets with cathode ray tubes instead of LCD screens) severely distorts its picture by altering the path of the electrons that make its…With a figure

College Physics22.6 The Hall Effect

Example 22.3Calculating the Hall emf: Hall Effect for Blood FlowA Hall effect flow probe is placed on an artery, applying a 0.100-T magnetic field across it, in a setup similar to that in Figure 22.29. What is the Hall emf, given the vessel’s inside diameter is 4.00 mm and the…

College Physics22.7 Magnetic Force on a Current-Carrying Conductor

Example 22.4Calculating Magnetic Force on a Current-Carrying Wire: A Strong Magnetic FieldCalculate the force on the wire shown in Figure 22.30, given B=1.50 T, l=5.00 cm, and I=20.0A.

College Physics22.8 Torque on a Current Loop: Motors and Meters

Example 22.5Calculating Torque on a Current-Carrying Loop in a Strong Magnetic FieldFind the maximum torque on a 100-turn square loop of a wire of 10.0 cm on a side that carries 15.0 A of current in a 2.00-T field.

College Physics22.9 Magnetic Fields Produced by Currents: Ampere’s Law

Example 22.6Calculating Current that Produces a Magnetic FieldFind the current in a long straight wire that would produce a magnetic field twice the strength of the Earth’s at a distance of 5.0 cm from the wire.
Example 22.7Calculating Field Strength inside a SolenoidWhat is the field inside a 2.00-m-long solenoid that has 2000 loops and carries a 1600-A current?

College Physics23.2 Faraday’s Law of Induction: Lenz’s Law

Example 23.1Calculating Emf: How Great Is the Induced Emf?Calculate the magnitude of the induced emf when the magnet in Figure 23.7(a) is thrust into the coil, given the following information: the single loop coil has a radius of 6.00 cm and the average value of Bcosθ (this…

College Physics23.3 Motional Emf

Example 23.2Calculating the Large Motional Emf of an Object in OrbitFigure 23.12 Motional emf as electrical power conversion for the space shuttle is the motivation for the Tethered Satellite experiment. A 5 kV emf was predicted to be induced in the 20 km long tether while moving at…With a figure

College Physics23.5 Electric Generators

Example 23.3Calculating the Emf Induced in a Generator CoilThe generator coil shown in Figure 23.20 is rotated through one-fourth of a revolution (from θ = 0º to θ = 90º) in 15.0 ms. The 200-turn circular coil has a 5.00 cm radius and is in a uniform 1.25 T magnetic field.…With a figure
Example 23.4Calculating the Maximum Emf of a GeneratorCalculate the maximum emf, emf0, of the generator that was the subject of Example 23.3.

College Physics23.7 Transformers

Example 23.5Calculating Characteristics of a Step-Up TransformerA portable x-ray unit has a step-up transformer, the 120 V input of which is transformed to the 100 kV output needed by the x-ray tube. The primary has 50 loops and draws a current of 10.00 A when in use. (a) What is…
Example 23.6Calculating Characteristics of a Step-Down TransformerA battery charger meant for a series connection of ten nickel-cadmium batteries (total emf of 12.5 V DC) needs to have a 15.0 V output to charge the batteries. It uses a step-down transformer with a 200-loop primary…

College Physics23.9 Inductance

Example 23.7Calculating the Self-inductance of a Moderate Size SolenoidCalculate the self-inductance of a 10.0 cm long, 4.00 cm diameter solenoid that has 200 coils.
Example 23.8Calculating the Energy Stored in the Field of a SolenoidHow much energy is stored in the 0.632 mH inductor of the preceding example when a 30.0 A current flows through it?

College Physics23.10 RL Circuits

Example 23.9Calculating Characteristic Time and Current in an RL Circuit(a) What is the characteristic time constant for a 7.50 mH inductor in series with a 3.00 Ω resistor? (b) Find the current 5.00 ms after the switch is moved to position 2 to disconnect the battery, if it is initially…

College Physics23.11 Reactance, Inductive and Capacitive

Example 23.10Calculating Inductive Reactance and then Current(a) Calculate the inductive reactance of a 3.00 mH inductor when 60.0 Hz and 10.0 kHz AC voltages are applied. (b) What is the rms current at each frequency if the applied rms voltage is 120 V?
Example 23.11Calculating Capacitive Reactance and then Current(a) Calculate the capacitive reactance of a 5.00 µF capacitor when 60.0 Hz and 10.0 kHz AC voltages are applied. (b) What is the rms current if the applied rms voltage is 120 V?

College Physics23.12 RLC Series AC Circuits

Example 23.12Calculating Impedance and CurrentAn RLC series circuit has a 40.0 Ω resistor, a 3.00 mH inductor, and a 5.00 μF capacitor. (a) Find the circuit’s impedance at 60.0 Hz and 10.0 kHz, noting that these frequencies and the values for L and C are the…
Example 23.13Calculating Resonant Frequency and CurrentFor the same RLC series circuit having a 40.0 Ω resistor, a 3.00 mH inductor, and a 5.00 μF capacitor: (a) Find the resonant frequency. (b) Calculate Irms at resonance if Vrms is 120 V.
Example 23.14Calculating the Power Factor and PowerFor the same RLC series circuit having a 40.0 Ω resistor, a 3.00 mH inductor, a 5.00 μF capacitor, and a voltage source with a Vrms of 120 V: (a) Calculate the power factor and phase angle for f=60.0Hz. (b) What is…