Junior Assessment Exam
1) A solid block of metal is placed in a uniformed electric field. Select the statement that is correct
concerning the electric field in the interior of the block.
A. The interior field points opposite to the exterior field
B.
C.
D.
E.
The interior field points in a direction perpendicular to the exterior field
The interior field points parallel to the exterior field
The interior field is zero
The interior field will depend on the charge distribution on the surface of the metal
2) A proton (=
q 1.6 × 10−19 C) moves from a place where the potential is 100 V to a point where the
potential is 80 V. The work done by the electric field is
A. 2.88 × 10−17 J
B. -180 eV
C. 3.2 × 10−18 J
D. 20 eV
E. -20 eV
3) Taking g = 10 m/s, if a jet plane does a loop-the-loop at a constant speed of 720 km/h and the radius
of the circle is 1km, what is the acceleration at the bottom?
A.
B.
C.
D.
E.
g
4g
6g
8g
16g
4) A simple pendulum, consisting of a mass m and a string of length l , swings upward, makes an angle
θ with the vertical. The work done by the tension force is
l
θ
A. mg l cos(θ)
B. mg l sin(θ)
C. mg l sin(θ/2)
D. mg l
E. zero
5) A 4 kg mass moving with speed 2 m/s, and a 2 kg mass moving with a speed of 4 m/s, are gliding
over a horizontal frictionless surface. Both objects encounter the same horizontal force, which
directly opposes their motion, and are brought to rest by it. Which statement best describes their
respective stopping distances?
A. The 4 kg mass travels twice as far as the 2 kg mass before stopping
B. The 2 kg mass travels twice as far as the 4 kg mass before stopping
C. Both masses travel the same distance before stopping
D. The 4 kg mass travels greater than twice as far
E. The 2 kg mass travels greater than twice as far
6) Assume that the density of air is a constant 1.3 kg/m 3 and that the air pressure is
1 x 105 N/m2 or 76 cm of Hg. What is the pressure at the top of a 500 meter high skyscraper?
A.
B.
C.
D.
E.
75 cm of Hg
74 cm of Hg
73 cm of Hg
72 cm of Hg
71 cm of Hg
7) A square is 1.0 m on a side. Charges of 4.0 µC are placed in two diagonally opposite corners and
charges of +3.0 µC are placed in the other two diagonally opposite corners. The potential in the center
of the square is:
A.
B.
C.
D.
E.
(=
k 9.0 × 109 N·m 2 / C2 )
0V
1.0 × 105 V
5.1 × 104 V
7.6 × 104 V
9.9 ×104 V
8) The length of a wire is doubled and the radius is doubled. The resistance becomes
A.
B.
C.
D.
E.
twice as large
four times as large
half as large
quarter as large
the same
9) In the figure, the volume at point “c” is 0.8 m3 and the pressure is 2.0 × 105 N/m2. The volume at “a”
is 0.4 m3 and the pressure is 5.0 × 105 N/m2. What is the work done as the system goes through the
complete cycle abcda?
A.
B.
C.
D.
E.
4.0 × 105 J
1.2 × 105 J
0J
−1.2 × 105 J
−4.0 × 105 J
10) Referring to the previous problem, what heat is absorbed by the system in the above square cycle?
A. 4.0 × 105 J
B. 1.2 × 105 J
C. 0 J
D. −1.2 × 105 J
E. −4.0 × 105 J
11) For an electron moving in a direction opposite to the electric field
A.
B.
C.
D.
E.
The potential energy increases and the potential decreases
The potential energy decreases and the potential increases
The potential energy increases and the potential increases
The potential energy decreases and the potential decreases
The potential energy decreases but the potential remains the same
12) An ice skater is in a spin with his arms outstretched. If he pulls in his arms,
A.
B.
C.
D.
E.
both his rotational kinetic energy and his angular momentum remain constant
his kinetic energy remains constant but his angular momentum increases
his rotational kinetic energy increases and his angular momentum increases
his rotational kinetic energy decreases and his angular momentum remains constant
his rotational kinetic energy increases but his angular momentum remains constant
13) At a particular instant, an electron moves eastward with velocity v in a uniform magnetic field B that
is directed into the plane. The magnetic force that acts on the electron is
A.
B.
C.
D.
E.
zero
pointing out of the plane
pointing into the plane
pointing south
pointing north
14) Six volts are applied to a 2 resistor in series with two 2 resistors connected in parallel. The current
through the first resistor is
A.
B.
C.
D.
E.
4A
3A
2A
1A
0.5 A
15) Magnetic field lines about a current-carrying wire
A.
B.
C.
D.
E.
circle the wire in closed loops
point radially outward from the wire
point radially inward into the wire
point along the wire parallel to the current
point along the wire opposite to the current
16) If you release a ball inside a freely-falling elevator it stays in front of you instead of falling to the
floor of the elevator, because you, the ball, the elevator and the air in the elevator are all in free fall. If you
release a helium filled balloon, it will
A.
B.
C.
D.
E.
press against the ceiling of the elevator
press against the floor of the elevator
drift down slowly
stay in front of you also
drift up slowly
17) An egg is placed at the bottom of a bowl filled with water. Salt is slowly added to the water until the
egg rises and floats. The best explanation for this is that the
A.
B.
C.
D.
E.
calcium in the egg shell is repelled by salt
density of salt water exceeds the density of the egg
buoyant force does not always act upward
egg absorbs the salt and expanded
density of the egg exceeds the density of salt water
18) A stone is whirled in a vertical circle on a cord. Halfway up
(a)
(b)
(c)
(d)
(e)
the tension is towards the center of the circle and the net force is down
the weight is down and the net force is towards the center of the circle
the tension force is towards the center of the circle and the weight is down
the weight and tension are in the same direction
the tension force is away from the center of the circle and the weight is down
19) A driver is 1.2 m beneath the surface of a still pond. At what angle, with respect to the normal, must
the driver shine a beam of light toward the surface in order for a person in a distant bank to see it?
(n=1.33, water)
(a)
(b)
(c)
(d)
(e)
49°
41°
59°
90°
0°
20) A monochromatic light is incident on a double slit setup that has a slit separation of 30.0 µ m . The
separation between two consecutive bright fringes is 2.15 cm on a screen 1.20 m from the double slit. The
wavelength of the light is
F.
G.
H.
I.
J.
269 nm
807 nm
538 nm
600 nm
403 nm
21) An object is placed on an inclined plane. The angle of incline is gradually increased until the object
begins to slide. The angle at which this occurs is θ. What is the coefficient of the static friction between
the object and plane?
(a)
(b)
(c)
(d)
(e)
sin(θ)
cos(θ)
tan(θ)
sin(θ/2)
cos(θ/2)
22) Both blocks A and B have mass m. In the figure the normal force on block B is
(a)
(b)
(c)
(d)
mg sin(θ)
mg sin(ϕ)
mg cos(θ)
mg sin(θ +
ϕ)
(e) mg cos(ϕ)
23) The specific heat of glass is 0.2 cal/g ° C . If you put 1 kg of glass in contact with an equal mass of
water and its temperature drops 5 ° C , by how much will the temperature of the water rise?
(a)
(b)
(c)
(d)
(e)
1 °C
2 °C
4 °C
5 °C
10 ° C
24) If the speed of sound is 350 m/s and the wavelength is 10 cm, what is the frequency?
(a)
(b)
(c)
(d)
(e)
35 Hz
175 Hz
350 Hz
1750 Hz
3500 Hz
25) What is the magnitude of the torque exerted by F force on the rod?
(a)
(b)
(c)
(d)
(e)
0 N-m
5 N-m
8.7 N-m
10 N-m
17.3 N-m
26) 10 moles of gas have a gauge pressure of 2 atm and a temperature of 200 K. If the temperature is
doubled keeping the volume constant, what will be new gauge pressure in atm?
(a)
(b)
(c)
(d)
(e)
2 atm
3 atm
4 atm
5 atm
6 atm
27) A reservoir delivers 1000 J of heat to another reservoir at 133 ° C . What is the increase in entropy of
the second reservoir?
(a)
(b)
(c)
(d)
(e)
7.52 J/K
2.5 J/K
1000 J/K
133000 J/K
406000 J/K
28) An object is placed 15 cm from a concave mirror of focal length 20 cm. The object is 4.0 cm tall.
What is the magnification?
(a)
(b)
(c)
(d)
(e)
0.25
0.5
2
3
4
29) Two bodies of equal mass are separated by a distance R. If you double the distance between them the
new gravitational force will be
(a)
(b)
(c)
(d)
(e)
twice the old force
half the old force
four times the old
one fourth the old
the same as the old force
30) A simple pendulum, consisting of a mass 2 kg, is attached to the end of a 1.5 m length of string. If the
mass is held out horizontally, and then released from rest, its speed at the bottom is
(a)
(b)
(c)
(d)
(e)
4.4 m/s
5.4 m/s
9.8 m/s
17 m/s
19 m/s
31) A 12000 kg railroad car traveling at 10 m/s strikes and couples with a 6000 kg caboose at rest. What
is the speed of the final combination?
(a)
(b)
(c)
(d)
(e)
3.3 m/s
5.0 m/s
6.7 m/s
10 m/s
44 m/s
32) According to Lenz’s law, the direction of an induced current in a conductor will be that which tends
to produce which of the following effects:
(a)
(b)
(c)
(d)
(e)
enhances the effect which produces it
decreases the flux linkage
produces the greatest induced emf
increases the flux linkage
opposes the effect which produces it
33) An electron moves with a velocity of 8.0 × 106 m/s along the positive x-axis. It enters a region
where the magnetic field of 2.5 T is directed at an angle of 600 to the positive x-axis. The magnetic force
on the electron is:
(a)
(b)
(c)
(d)
(e)
3.2 × 10−12
1.4 × 10−12
5.5 × 10−12
1.6 × 10−12
2.8 × 10−12
N
N
N
N
N
34) When a meter stick moves past you in the direction of its length, you measure it to be 90 cm long.
What is its speed?
(a)
(b)
(c)
(d)
(e)
9.5 ×107 m/s
2.7 ×107 m/s
5.7 ×107 m/s
1.3 ×107 m/s
2.4 ×107 m/s
35) A pion lives 26 ns in its rest frame before decaying. To an observer in a laboratory in which the
particle moves at a speed of 2.7 × 108 m/s, the particle lives for
(a)
(b)
(c)
(d)
(e)
60 ns
79 ns
15 ns
11 ns
43 ns
36) The photoelectric threshold of a certain metal is 310 nm. (Planck’s constant h = 6.626 x 10-34 Js) The
maximum kinetic energy of electrons ejected from the surface of the metal by ultraviolet light of
wavelength 200 nm is
(a)
(b)
(c)
(d)
(e)
60 ns
79 ns
15 ns
11 ns
43 ns
37) What is the momentum of a photon of wavelength equal to 560 nm? (Planck’s constant h = 6.626 x
10-34 Js)
(a)
(b)
(c)
(d)
(e)
60 ns
79 ns
15 ns
11 ns
43 ns
38) The energy of the n = 1 level of the hydrogen atom is -13.6 eV. The energy of the n = 4 level is
(a)
(b)
(c)
(d)
(e)
-3.4 eV
-54.4 eV
-0.85 eV
-6.8 eV
-27.2 eV
39) An electron in the hydrogen atom (ground-state energy = -13.6 eV) makes a transition from the n = 3
to the n = 1 energy level. Calculate the magnitude of the energy of the photon involved in this process and
state whether the photon was absorbed or emitted.
(a)
(b)
(c)
(d)
(e)
109 eV emitted
12.1 eV absorbed
15.2 eV absorbed
109 eV absorbed
12.1 eV emitted
40) The visible portion of the electromagnetic spectrum extends from
(a)
(b)
(c)
(d)
(e)
400 nm to 700 nm
300 nm to 600 nm
600 nm to 900 nm
200 nm to 500 nm
500 nm to 800 nm
41) According to the Bohr theory, a hydrogen atom
(a) remains in the ground state until it gives off a photon
(b) has an electron in the ground state, an electron in the n = 1 state, an electron in the n
= 2 state, and so on
(c) does not radiate when it is in a stationary state
(d) radiates when the electron accelerates in a circular orbit
(e) gives off a continuous spectrum from the K-shell
42) The radius of the n = 1 Bohr orbit in the hydrogen atom is 0.053 nm. What is the radius of the n = 5
Bohr orbit?
(a)
(b)
(c)
(d)
(e)
5 x (0.053) nm
25 x (0.053) nm
(1/5) x (0.053) nm
(1/25) x (0.053) nm
1 x (0.053) nm
43) The wave function for a particle in a one-dimensional box of length L
(a) must be zero everywhere outside the box
(b) restricts the possible energy of the particle to E =  2 k 2 / 2m
0 and Ψ ( L ) =
0
(c) is constrained by the boundary conditions Ψ ( 0 ) =
A sin ( kx ) where A is a constant
(d) is given by Ψ ( x ) =
(e) all of the above
44) The ground-state wave function of the harmonic oscillator has the following form (where A0 and a are
constants):
( )
(a) Ψ 0 ( x ) =
A0 sin ax 2
(b) Ψ 0 ( x ) =
A0 e − ax
2
A0 e − ax
(c) Ψ 0 ( x ) =
A0 sin ( ax )
(d) Ψ 0 ( x ) =
(e) Ψ 0 ( x ) =
A0 e ax
2
45) Which of the following experiment(s) illustrate the particle nature of light?
I.
II.
III.
Young’s double slit experiment
Photoelectric effect
Compton scattering
(a)
(b)
(c)
(d)
(e)
I and II only
II and III only
III only
II only
I only