Question 1

A loop of wire is oscillating up and down in a uniform magnetic field. Which of the following best describes the induced EMF in the loop?

Accepted Answer

The induced EMF varies sinusoidally with time as $$\frac{d\Phi}{dt}$$ changes.

Question 2

Which equation correctly relates the induced EMF ($$\mathcal{E}) in a $$loop to the change in magnetic flux ($$\Phi$$)?

Accepted Answer

$$\mathcal{E} = \frac{d\Phi}{dt}$$

Question 3

A square loop of wire of area $$A is $$placed in a uniform magnetic field $$B$$ perpendicular to the plane of the loop. If the magnetic field changes from $$B_0 to$$ $$B_1 in $$time $$t$$, what is the average induced EMF?

Accepted Answer

$$\mathcal{E} = \frac{A(B_1$ - B_0$)}{t}$$

Question 4

Two long wires carry equal currents $$I in $$opposite directions. What is the direction of the net magnetic field at a point equidistant from both wires?

Accepted Answer

The net magnetic field points in the direction given by the vector sum of the individual fields.

Question 5

An electron moves parallel to a wire carrying a current. If the electron is moving at velocity $$v$$ and is a distance $$d$$ from the wire, what is the magnitude of the magnetic field at the electron's location?

Accepted Answer

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

Question 6

A light beam passes through a slit and illuminates a screen. If the slit width is decreased, what happens to the width of the central maximum?

Accepted Answer

The width of the central maximum increases.

Question 7

In a double-slit experiment, the distance between the slits is $$d$$, the wavelength of light is $$\lambda$$, and the screen is at distance $$L. $$What is the formula for the position of the $$m-th $$bright fringe?

Accepted Answer

$$y_m = \frac{m \lambda L}{d}$$

Question 8

A diffraction grating is used to resolve two wavelengths $$\$$lambda_1$$ and $$\$$lambda_2. $$Which factor increases the resolving power of the grating?

Accepted Answer

Increasing the number of slits.

Question 9

A wire loop rotates in a uniform magnetic field. What is the expression for the maximum induced EMF?

Accepted Answer

$$\mathcal{E}_{max} = B A \omega$$

Question 10

If the magnetic flux through a loop is constant, what is the induced EMF?

Accepted Answer

The induced EMF is zero.

Question 11

An electron moving perpendicular to a magnetic field experiences a force. What is the direction of the force?

Accepted Answer

The force is perpendicular to both the velocity and the magnetic field.

Question 12

A light beam passes through a diffraction grating with $$N$$ slits. What is the formula for the angular position $$	heta of $$the $$m-th $$order maximum?

Accepted Answer

$$d \sin 	heta = m \lambda$$

Question 13

In a double-slit experiment, if the wavelength of light is doubled, what happens to the fringe spacing?

Accepted Answer

The fringe spacing is doubled.

Question 14

A wire loop is placed in a region where the magnetic field is increasing. What is the direction of the induced current?

Accepted Answer

The induced current opposes the increase in magnetic flux (Lenz's Law).

Question 15

A light beam passes through a slit and forms a diffraction pattern. If the wavelength is increased, what happens to the width of the central maximum?

Accepted Answer

The width increases.

Question 16

A wire loop rotates in a magnetic field at angular frequency $$\omega. $$What is the time dependence of the induced EMF?

Accepted Answer

$$\mathcal{E}(t) = B A \omega \sin(\omega t)$$

Question 17

In a double-slit experiment, what happens to the intensity of the bright fringes if the slit separation is increased?

Accepted Answer

The intensity remains unchanged.

Question 18

A wire loop is placed in a region where the magnetic field is constant. What is the induced EMF?

Accepted Answer

The induced EMF is zero.

Question 19

An electron moves in a region with both electric and magnetic fields. If the velocity is perpendicular to both fields, what is the net force?

Accepted Answer

$$\vec{F} = q(\vec{E} + \vec{v} 	imes \vec{B})$$

Question 20

A diffraction grating produces a pattern on a screen. If the number of slits is doubled, what happens to the sharpness of the maxima?

Accepted Answer

The maxima become sharper.

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