GRE Physics Sample Exam 1
GRE PHYSICS SAMPLE EXAM 1 NEWEST 2025/2026 COMPLETE
ALL 100 QUESTIONS AND CORRECT DETAILED ANSWERS
|ALREADY GRADED A+||ALREADY GRADED A+
Unpolarized light is incident on a pair of ideal linear polarizers whose transmission
axes make an angle of 45 degrees with each other. The transmitted light intensity
through both polarizers is what percentage of the incident intensity?
(A) 100% (B) 75% (C) 50% (D) 25% (E) 0%
The transmitted light is (1 - cos(angle))% = (1 - cos(45)) = 25%. The transmitted
light intensity through both polarizers is 25% of the incident intensity. Choice (D).
A very long, thin, straight wire carries a uniform charge density of lambda per unit
length. Which of the following gives the magnitude of the electric field at a radial
distance r from the wire?
The electric field about the outside of a wire should decrease as the distance from
the wire decreases, which gives us the radius found in the denominator, which is
given by choice (A) as (1/2pie)*lambda/r.
A bar magnet shown in the figure above is moved completely through the loop.
Which of the following is a true statement about the direction of the current flow
between the two points a and b in the circuit?
(A) No current flows between a and b as the magnet passes through the loop.
(B) Current flows from a to b as the magnet passes through the loop.
(C) Current flows from b to a as the magnet passes through the loop.
(D) Current flows from a to b as the magnet enteres the loop and from b to a as
the magnet leaves the loop.
(E) Current flows from b to a as the magnet enters the loop and from a to b as the
magnet leaves the loop.
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, GRE Physics Sample Exam 1
The vectors in the orthogonal basis of the force, magnetic field, and current
indicated by the right-hand rule from b to a as the magnet goes into the loop and
vice-versa. Choice (E).
The surface of the Sun has a temperature close to 6,000 K and it emits a
blackbody (Planck) spectrum that reaches a maximum near 500 nm. For a body
with a surface temperature close to 300 K, at what wavelength would the thermal
spectrum reach a maximum?
(A) 10 um (B) 100 um (C) 10 mm (D) 100 mm (E) 10 m
You love ratios GRE, don't you. (500 nm)(6,000 K/300 K) = 10 um. This is similar to
a combined gas law question, but choice (A) is the winner.
At the present time, the temperature of the universe (i.e., the microwave
radiation background) is about 3 K. When the temperature was 12 K, typical
objects in the universe, such as galaxies, were
(A) one-quarter as distant as they are today
(B) one-half as distant as they are today
(C) separated by about the same distances as they are today
(D) two times as distant as they are today
(E) four times as distant as they are today
The universe was much more condensed and much hotter billions of years ago at
the genesis of creation. (3 K)/(12 K) = 1/4, which gives us the galaxies were one-
quarter as distant as they are today. Choice (A).
For an adiabatic process involving an ideal gas having volume V and temperature
T, which of the following is constant? (y = Cp/Cv)
(A) TV
(B) TV^y
(C) TV^(y - 1)
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, GRE Physics Sample Exam 1
(D) (T^y)V
(E) (T^y)V^-1
Nice mix between thermodynamics and vibrations and waves gives us the
constant T*V^(y - 1). Choice (C).
An electron has total energy equal to four times its rest energy. The momentum of
the electron is
(A) mc
(B) sqrt(2)mc
(C) sqrt(15)mc
(D) 4mc
(E) 2sqrt(15)m*c
Pythagorean analogues again gives us sqrt(4^2 - 1^2) = sqrt(16 - 1) = sqrt(15),
given by choice (C).
Two spaceships approach Earth with equal speeds as measured by an observer on
Earth, but from opposite directions. A meterstick on one spaceship is measured to
be 60 cm long by an occupant of the other spaceship. What is the speed of each
spaceship, as measured by the observer on Earth?
(A) 0.4c (B) 0.5c (C) 0.6c (D) 0.7c (E) 0.8c
Einstein's velocity addition rule gives us: (x^2)/(1 - x^2) = 0.6, which gives us 0.6 =
1.6x^2 => x = sqrt(3/8) = sqrt(0.375) = 0.6
A meter stick with a speed of 0.8c moves past an observer. In the observer's
reference frame, how long does it take the stick to pass the observer?
(A) 1.6 ns (B) 2.5 ns (C) 4.2 ns (D) 6.9 ns (E) 8.3 ns
Time dilation: y = (1 - 0.8^2)^-0.5 = 5/3. So the new time (t') is t' = (5/3)t. v = x/t =>
t = x/v = t' = 3x/5v = (3/5)(1 m)/(2.4E8 m/s) = 2.5E-9 s =2.5 ns. Choice (B)
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GRE PHYSICS SAMPLE EXAM 1 NEWEST 2025/2026 COMPLETE
ALL 100 QUESTIONS AND CORRECT DETAILED ANSWERS
|ALREADY GRADED A+||ALREADY GRADED A+
Unpolarized light is incident on a pair of ideal linear polarizers whose transmission
axes make an angle of 45 degrees with each other. The transmitted light intensity
through both polarizers is what percentage of the incident intensity?
(A) 100% (B) 75% (C) 50% (D) 25% (E) 0%
The transmitted light is (1 - cos(angle))% = (1 - cos(45)) = 25%. The transmitted
light intensity through both polarizers is 25% of the incident intensity. Choice (D).
A very long, thin, straight wire carries a uniform charge density of lambda per unit
length. Which of the following gives the magnitude of the electric field at a radial
distance r from the wire?
The electric field about the outside of a wire should decrease as the distance from
the wire decreases, which gives us the radius found in the denominator, which is
given by choice (A) as (1/2pie)*lambda/r.
A bar magnet shown in the figure above is moved completely through the loop.
Which of the following is a true statement about the direction of the current flow
between the two points a and b in the circuit?
(A) No current flows between a and b as the magnet passes through the loop.
(B) Current flows from a to b as the magnet passes through the loop.
(C) Current flows from b to a as the magnet passes through the loop.
(D) Current flows from a to b as the magnet enteres the loop and from b to a as
the magnet leaves the loop.
(E) Current flows from b to a as the magnet enters the loop and from a to b as the
magnet leaves the loop.
1|Page
, GRE Physics Sample Exam 1
The vectors in the orthogonal basis of the force, magnetic field, and current
indicated by the right-hand rule from b to a as the magnet goes into the loop and
vice-versa. Choice (E).
The surface of the Sun has a temperature close to 6,000 K and it emits a
blackbody (Planck) spectrum that reaches a maximum near 500 nm. For a body
with a surface temperature close to 300 K, at what wavelength would the thermal
spectrum reach a maximum?
(A) 10 um (B) 100 um (C) 10 mm (D) 100 mm (E) 10 m
You love ratios GRE, don't you. (500 nm)(6,000 K/300 K) = 10 um. This is similar to
a combined gas law question, but choice (A) is the winner.
At the present time, the temperature of the universe (i.e., the microwave
radiation background) is about 3 K. When the temperature was 12 K, typical
objects in the universe, such as galaxies, were
(A) one-quarter as distant as they are today
(B) one-half as distant as they are today
(C) separated by about the same distances as they are today
(D) two times as distant as they are today
(E) four times as distant as they are today
The universe was much more condensed and much hotter billions of years ago at
the genesis of creation. (3 K)/(12 K) = 1/4, which gives us the galaxies were one-
quarter as distant as they are today. Choice (A).
For an adiabatic process involving an ideal gas having volume V and temperature
T, which of the following is constant? (y = Cp/Cv)
(A) TV
(B) TV^y
(C) TV^(y - 1)
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, GRE Physics Sample Exam 1
(D) (T^y)V
(E) (T^y)V^-1
Nice mix between thermodynamics and vibrations and waves gives us the
constant T*V^(y - 1). Choice (C).
An electron has total energy equal to four times its rest energy. The momentum of
the electron is
(A) mc
(B) sqrt(2)mc
(C) sqrt(15)mc
(D) 4mc
(E) 2sqrt(15)m*c
Pythagorean analogues again gives us sqrt(4^2 - 1^2) = sqrt(16 - 1) = sqrt(15),
given by choice (C).
Two spaceships approach Earth with equal speeds as measured by an observer on
Earth, but from opposite directions. A meterstick on one spaceship is measured to
be 60 cm long by an occupant of the other spaceship. What is the speed of each
spaceship, as measured by the observer on Earth?
(A) 0.4c (B) 0.5c (C) 0.6c (D) 0.7c (E) 0.8c
Einstein's velocity addition rule gives us: (x^2)/(1 - x^2) = 0.6, which gives us 0.6 =
1.6x^2 => x = sqrt(3/8) = sqrt(0.375) = 0.6
A meter stick with a speed of 0.8c moves past an observer. In the observer's
reference frame, how long does it take the stick to pass the observer?
(A) 1.6 ns (B) 2.5 ns (C) 4.2 ns (D) 6.9 ns (E) 8.3 ns
Time dilation: y = (1 - 0.8^2)^-0.5 = 5/3. So the new time (t') is t' = (5/3)t. v = x/t =>
t = x/v = t' = 3x/5v = (3/5)(1 m)/(2.4E8 m/s) = 2.5E-9 s =2.5 ns. Choice (B)
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