Questions from College Physics

Q: A motor has coils with a resistance of 30. Ω and

A motor has coils with a resistance of 30. Ω and operates from a voltage of 240 V. When the motor is operating at its maximum speed, the back emf is 145 V. Find the current in the coils (a) When the m...

Q: A coil of 10.0 turns is in the shape of

A coil of 10.0 turns is in the shape of an ellipse having a major axis of 10.0 cm and a minor axis of 4.00 cm. The coil rotates at 100. rpm in a region in which the magnitude of Earth’s magnetic field...

Q: A solenoid with 475 turns has a length of 6.00

A solenoid with 475 turns has a length of 6.00 cm and a cross-sectional area of 2.80 x 10-9 m2. Find (a) The solenoid’s inductance and (b) The average emf around the solenoid if the current changes fr...

Q: The current in a coil drops from 3.5 A to

The current in a coil drops from 3.5 A to 2.0 A in 0.50 s. If the average emf induced in the coil is 12 mV, what is the self-inductance of the coil?

Q: A loop of wire is placed in a uniform magnetic field.

A loop of wire is placed in a uniform magnetic field. (a) For what orientation of the loop is the magnetic flux a maximum? (b) For what orientation is the flux zero?

Q: Show that the two expressions for inductance given by L = NфB

Show that the two expressions for inductance given by L = NфB/I and L = -ε / ΔI/Δt have the same units.

Q: A solenoid of radius 2.5 cm has 400 turns and

A solenoid of radius 2.5 cm has 400 turns and a length of 20 cm. Find (a) Its inductance and (b) The rate at which current must change through it to produce an emf of 75 mV.

Q: An emf of 24.0 mV is induced in a 500

An emf of 24.0 mV is induced in a 500-turn coil when the current is changing at a rate of 10.0 A/s. What is the magnetic flux through each turn of the coil at an instant when the current is 4.00 A?

Q: An electromagnet can be modeled as an inductor in series with a

An electromagnet can be modeled as an inductor in series with a resistor. Consider a large electromagnet of inductance L = 12.0 H and resistance R = 4.50 Ω connected to a 24.0 V battery an...

Q: An RL circuit with L = 3.00 H and an

An RL circuit with L = 3.00 H and an RC circuit with C = 3.00 μF have the same time constant. If the two circuits have the same resistance R, (a) What is the value of R and (b) What is this common tim...