🏷️ LIMITED TIME OFFER: GET 20% OFF GRADE+ YEARLY SUBSCRIPTION →
Log in
Physics
4
answers
1
watching
820
views

Which statement is true of magnets?

a) Earth is an electromagnet

b) Electromagnets are weaker than permanant magnets

c) A magnet always has a north pole, and may or may not also has a south pole

d) A permanent magnet can be turned off.

Watch
4
answers
1
watching
820
views

For unlimited access to Homework Help, a Homework+ subscription is required.

Unlock all answers

Get 1 free homework help answer.
Already have an account? Log in
Share
Already have an account? Log in
Share
Already have an account? Log in
Share
Jarrod Robel
Jarrod RobelLv2
22 Feb 2020
Already have an account? Log in
Share

Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

The figure shows a coil made of a wire wrapped around a cylindrical object. The coil is connected to the battery and a current flows in the wire. The current flows out of the + terminal and into the - terminal of the battery, making the coil an electromagnet. One end of the coil becomes a north pole and the other becomes a south pole. Use a right-hand rule to figure out which poles are on which sides of the coil.

a)The north pole is on the left and the south pole is on the right.

b)The north pole is on the right and the south pole is on the left.

c)Both ends are north poles.

d)Both ends are south poles.

 

Which best describes Earth’s magnetic field lines?

(a) The field lines go out of Earth near the South Pole, enter Earth in the North Pole, and are aligned with the geographic poles.

(b) The field lines go out of Earth near the South Pole, enter Earth in the North Pole, and are not aligned with the geographic poles.

(c) The field lines go out of Earth near the North Pole, enter Earth in the South Pole, and are aligned with the geographic poles.

(d) The field lines go out of Earth near the North Pole, enter Earth in the South Pole, and are not aligned with the geographic poles.

Your camping buddy has an idea for a light to go inside your tent. He happens to have a powerful (and heavy!) horseshoe magnet that he bought at a surplus store. This magnet creates a B = 0.20 T field between two pole tips 10 cm apart. His idea is to build a hand-cranked generator shown in Figure. He thinks you can make enough current to fully light a R = 1.0 Ω? lightbulb rated at 4.0W. That's not super bright, but it should be plenty of light for routine activities in the tent.

A. Find an expression for the induced current as a function of time if you turn the crank at frequency f. Assume that the semicircle has a radius of r = 5.0 cm and it is at its highest point at t = 0 s. Express your answer in terms of some or all of the variables B, R, r, f, t, and the constant ?.

B. With what frequency will you have to turn the crank for the maximum current to fully light the bulb?

C. Is this feasible? (Yes or no)

Weekly leaderboard

Home
Homework Help 3,900,000
Physics 110,000
Start filling in the gaps now
Log in