Q: A long straight wire carries a current $$I = 5.0\ \mathrm{A}$$, and a particle with charge $$q = +6e is $$moving parallel to the wire at a distance $$r = 0.020\ \mathrm{m}$$ with speed $$v = 3.8 \times 10^6$\ \mathrm{m/s}. $$What is the magnitude and direction of the magnetic force on the particle?

$$3.0 \times 10$$^{-17}$$\ \mathrm{N}$$, outward

Question 1

A conductor is moved at a constant velocity $$v$$ through a uniform magnetic field $$B ($$out of the page), along two conducting rails separated by a distance $$L$$ and connected to a resistor $$R$$, as shown in the first image. If $$v = 8.00\ \mathrm{m/s}$$, $$B = 1.30\ \mathrm{T}$$, $$L = 1.70\ \mathrm{m}$$, and $$R = 56.0\ \Omega$$, what is the magnitude of the induced current in the circuit?

Accepted Answer

$$0.316\ \mathrm{A}$$

Question 2

Refer to the first image. What is the direction of the induced current in the resistor $$R as $$the bar moves to the right?

Accepted Answer

Clockwise

Question 3

A circular loop of copper wire is placed near a wire carrying current $$I ($$see the second image). If the loop is moved at a constant speed, in which direction would result in zero current induced in the loop?

Accepted Answer

Direction 1 (parallel to wire)

Question 4

A long straight wire carries a current $$I = 5.0\ \mathrm{A}$$, and a particle with charge $$q = +6e is $$moving parallel to the wire at a distance $$r = 0.020\ \mathrm{m}$$ with speed $$v = 3.8 	imes 10^6$\ \mathrm{m/s}. $$What is the magnitude and direction of the magnetic force on the particle?

Accepted Answer

$$3.0 	imes 10$$^{-17}$$\ \mathrm{N}$$, outward

Question 5

Light with a frequency of $$6.20 	imes 10$$^{14}$$\ \mathrm{Hz} is $$traveling in diamond with an index of refraction $$n = 2.42. $$What is the wavelength of the light in the diamond?

Accepted Answer

$$200\ \mathrm{nm}$$

Question 6

Refer to the third image. An aquarium filled with water ($$n = 1.33) $$has flat glass sides ($$n = 1.65). A $$beam of light from air strikes the glass at $$30.0^{\circ} to $$the perpendicular. What is the angle of refraction as the ray enters the water?

Accepted Answer

$$22.1^{\circ}$$

Question 7

A laser pointer is immersed in a fluid with refractive index $$n = 3.0$$ with air above the surface. If the laser is aimed at $$40^{\circ}$$ from vertical, can any light emerge from the liquid into the air?

Accepted Answer

No, all light is totally internally reflected

Question 8

A diverging lens has a focal length of $$-32.0\ \mathrm{cm}. An $$object is placed $$19.0\ \mathrm{cm} in $$front of this lens. What is the image distance and is the image real or virtual?

Accepted Answer

$$-11.9\ \mathrm{cm}$$, virtual

Question 9

A person’s eye has a near point of $$60\ \mathrm{cm}. If $$the person uses a $$2.25$$ diopter lens, what is the closest distance (from the eye) the person can focus on an object? Assume the glasses are $$2.0\ \mathrm{cm} in $$front of the eye.

Accepted Answer

$$27\ \mathrm{cm}$$

Question 10

A single slit of width $$D = 0.00253\ \mathrm{mm}$$ has light of wavelength $$\lambda = 660\ \mathrm{nm}$$ incident on it. What is the angular width of the central intensity maximum projected onto a screen?

Accepted Answer

$$30.2^{\circ}$$

Question 11

Refer to the fourth image. If $$n_1$$ \u003c $$n_3$$ \u003c $$n_2$$, which equation represents the condition for total destructive interference between rays (2) and (5), where no light reaches the eye?

Accepted Answer

$$2t = m \dfrac{\lambda}{n_2$}$$

Question 12

Unpolarized light of intensity $$I_0$$ first passes through a horizontal polarizer and then through a polarizer oriented $$65^{\circ}$$ from the horizontal. What fraction of the light passes through both polarizers?

Accepted Answer

$$9\%$$

Question 13

A beam of light passes from air ($$n=1.00) $$into water ($$n=1.33) at an $$angle of $$45^{\circ} to $$the normal. What is the angle of refraction in the water?

Accepted Answer

$$32.1^{\circ}$$

Question 14

A thin film of oil ($$n=1.50) $$floats on water ($$n=1.33). $$For what minimum nonzero thickness will the film appear dark for light of wavelength $$600\ \mathrm{nm} in $$air, assuming normal incidence?

Accepted Answer

$$100\ \mathrm{nm}$$

Question 15

A wire carries a current $$I to $$the left. A positively charged particle moves parallel to the wire in the same direction. What is the direction of the magnetic force on the particle?

Accepted Answer

Radially outward from the wire

Physics 1201: Midterm II Review – Step-by-Step Study Guidance

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