Question 1

A proton moves perpendicular to a uniform magnetic field with velocity $$v. $$What is the direction of the force acting on the proton?

Accepted Answer

Perpendicular to both the velocity and the magnetic field, determined by the right hand rule

Question 2

A wire carrying current $$I is $$placed in a magnetic field $$B. $$What is the formula for the force on the wire?

Accepted Answer

$$F = BIL$$

Question 3

A negative particle moves through a magnetic field. Which hand should you use to determine the direction of the force?

Accepted Answer

Left hand

Question 4

A charged particle moves in a circle in a magnetic field. Which equation relates the magnetic force to the centripetal force?

Accepted Answer

$$Bqv = \frac{mv^2$}{r}$$

Question 5

What is the purpose of a transformer in the power grid?

Accepted Answer

To increase voltage and decrease current

Question 6

Which equation describes the relationship between the number of turns and voltage in a transformer?

Accepted Answer

$$\frac{N_p}{N_s} = \frac{V_p}{V_s}$$

Question 7

A wire of length $$L$$ carrying current $$I is $$placed perpendicular to a magnetic field $$B. $$What is the magnitude of the force?

Accepted Answer

$$F = BIL$$

Question 8

A motor uses the force on a current-carrying wire in a magnetic field. Which rule determines the direction of the force?

Accepted Answer

Right hand rule

Question 9

If a wire is carrying current out of the page, which direction is the magnetic field around the wire?

Accepted Answer

Counterclockwise

Question 10

A conductor moves with velocity $$v$$ through a magnetic field $$B. $$What is the induced EMF?

Accepted Answer

$$EMF = BLv$$

Question 11

In electromagnetic induction, if the velocity is perpendicular to the magnetic field, which rule helps you find the direction of the induced current?

Accepted Answer

Right hand rule

Question 12

A transformer has 100 turns on the primary coil and 50 turns on the secondary coil. If the input voltage is 240 V, what is the output voltage?

Accepted Answer

120 V

Question 13

A positive ion moves to the right in a magnetic field pointing upward. What is the direction of the force?

Accepted Answer

Into the page

Question 14

Which formula would you use to calculate the magnetic field at a distance $$r$$ from a long straight wire carrying current $$I$$?

Accepted Answer

$$B = \frac{\mu_0$ I}{2\pi r}$$

Question 15

A transformer is used to step up the voltage from 120 V to 480 V. If the primary coil has 200 turns, how many turns should the secondary coil have?

Accepted Answer

800 turns

Question 16

A wire of length $$L$$ moves with velocity $$v$$ perpendicular to a magnetic field $$B. $$What is the induced EMF?

Accepted Answer

$$EMF = BLv$$

Question 17

If the current in a wire is reversed, what happens to the direction of the magnetic field around the wire?

Accepted Answer

It reverses direction

Question 18

A transformer has a primary current of 2 A and a secondary current of 0.5 A. If the primary voltage is 100 V, what is the secondary voltage?

Accepted Answer

400 V

Question 19

A wire carrying current $$I is $$placed in a magnetic field $$B at an $$angle $$	heta. $$What is the formula for the force?

Accepted Answer

$$F = BIL \sin 	heta$$

Question 20

A positive charge moves in a circle in a magnetic field. What determines the radius of the circle?

Accepted Answer

$$r = \frac{mv}{Bq}$$

Magnetism, Electromagnetic Induction, and Transformers: Study Notes

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