Practice Test

Please solve the following questions. This is not a real exam, it will not be graded, and you do not need to submit your solutions to anyone. The questions are simply intended to help you practice for the real exam.

These questions will not appear in the exam itself. Students who don't genuinely attempt to solve the questions on their own, and only memorize the solutions, will have a very hard time in the actual exam!

This sample exam is online, but the real exam will be given in person, at a time and place indicated on the course website.

THIS IS NOT THE ACTUAL EXAM!
THIS IS JUST A PRACTICE EXAM!
THE REAL EXAM IS IN PERSON!

If you need any clarifications for these questions, you can ask for them on the course Teams channel.

Question 1

Before the cosmic microwave background was released, the universe was...

Transparent.
Opaque.
Yellow.

Question 2

Which of the following objects bends spacetime the most?

The Sun.
The Moon.
The Earth.

Question 3

I live on the 24th floor. Compared to my friend who lives on the 12th floor, I experience time...

At a slower rate.
At the same rate.
At a faster rate.

Question 4

The relative velocity between Alice and Bob corresponds to a Lorentz factor of 5. Alice measures a proper time of 2 seconds between two events. How much time does Bob measure?

2 seconds.
10 seconds.
50 seconds.

Question 5

You are jumping from a tree down to the ground. According to the Einstein equivalence principle, while you are falling, you're...

In a non-inertial frame.
Not in any kind of frame.
In an inertial frame.

Question 6

Geodesics inside the event horizon...

Can point in any direction.
Can only point away from the center of the black hole.
Can only point toward the center of the black hole.

Question 7

Which of the following was observed by the Event Horizon Telescope?

M87*.
PSR B1919+21.
Cygnus X-1.

Question 8

What is an Einstein ring?

A light source that is being gravitationally lensed into a circular shape.
The ring that Einstein gave his first wife.
A light source that is being gravitationally lensed into 4 distinct copies.

Question 9

The Newtonian prediction for the perihelion precession of Mercury was...

Correct, because the curvature of spacetime is not relevant for this prediction.
Incorrect, because it did not take into account the curvature of spacetime.
Correct, because it took into account the curvature of spacetime.

Question 10

Galaxy A is twice as far from us compared to Galaxy B. According to Hubble's law, this means that Galaxy A...

Moves away from us twice as fast compared to Galaxy B.
Moves away from us half as fast compared to Galaxy B.
Moves away from us at the same speed as to Galaxy B.

Question 11

According to Kepler's second law, stars farther from the center of a galaxy should rotate...

At the same speed as stars closer to the center.
Faster than stars closer to the center.
Slower than stars closer to the center.

Question 12

What makes the expansion of the universe accelerate?

Dark energy.
Dark nebulae.
Dark matter.

Question 13

What is the Einstein cross?

The cross that Einstein gave his first wife as a Christmas gift.
A light source that is being gravitationally lensed into 4 distinct copies.
A light source that is being gravitationally lensed into a circular shape.

Question 14

Why don't we notice special-relativistic effects like time dilation in our daily lives?

Because we are moving at speeds much slower than the speed of light.
Because we are moving at speeds much faster than the speed of light.
Because our clocks compensate for these effects.

Question 15

How did LIGO provide evidence for gravitational waves in 2015?

Directly, by measuring the local influence of the gravitational wave itself on spacetime.
Directly, by detecting electromagnetic emission from the gravitational wave event.
Indirectly, by observing changes in the orbital period of a binary system.

Question 16

What was the significance of the gravitational wave event GW170817?

It was the first time both gravitational waves and electromagnetic waves were detected from the same source.
It was the first time a black hole was photographed.
It was the first time gravitational waves were detected directly.

Question 17

How did the Hulse-Taylor pulsar provide evidence for gravitational waves in 1974?

Question 18

What will be the advantage of putting a gravitational wave detector in space compared to detectors on Earth?

It will be sensitive to waves with much longer wavelengths.
It will be sensitive to waves with much shorter wavelengths.
The waves will not be blocked by interstellar dust.

Question 19

In Einstein's special theory of relativity, the speed of light in vacuum...

Is constant and independent of the observer, in contradiction with the predictions of electromagnetism.
Is constant and independent of the observer, consistent with the predictions of electromagnetism.
Depends on the observer, in contradiction with the predictions of electromagnetism.

Question 20

What is the difference between the weak equivalence principle and the Einstein equivalence principle?

The weak equivalence principle is formed in terms of mass, while the Einstein equivalence principle is formed in terms of energy.
The weak equivalence principle is formed in terms of mass, while the Einstein equivalence principle is formed in terms of acceleration.
The weak equivalence principle is formed in terms of acceleration, while the Einstein equivalence principle is formed in terms of mass.

Question 21

The Schwarzschild radius of a black hole with 10 solar masses is around 30 km. What is the Schwarzschild radius of a black hole with 30 solar masses?

150 km.
60 km.
90 km.

Question 22

In Eddington experiment, why was it important to measure the position of the stars at nighttime before the eclipse?

Because that was the only time during the year those stars could be seen.
Because at that time their light is not bent due to the curvature of spacetime.
Because that was the only time those stars could be seen next to the Sun.

Question 23

I live on the 3rd floor, and my friend lives on the 15th floor. If I send a radio wave to my friend, the wave will be...

Unaffected (my friend will see the same wavelength).
Redshifted (my friend will see a longer wavelength).
Blueshifted (my friend will see a shorter wavelength).

Question 24

What was the source of the gravitational wave event GW150914?

Two neutron stars merging.
A black hole and a neutron star merging.
Two black holes merging.

Question 25

Which of the following is a stellar black hole?

PSR B1919+21.
Cygnus X-1.
M87*.