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

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

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

Question 2

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 50 solar masses?

150 km.
90 km.
60 km.

Question 3

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

Question 4

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 gravitational waves were detected directly.
It was the first time a black hole was photographed.

Question 5

What is the Einstein cross?

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

Question 6

I live on the 23rd 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 7

When the cosmic microwave background was released, the universe became...

Opaque.
Yellow.
Transparent.

Question 8

Geodesics inside the event horizon...

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

Question 9

In the Eddington experiment, why was it important to measure the position of the stars during an eclipse?

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

Question 10

What was the source of the gravitational wave event GW170817?

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

Question 11

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

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

Question 12

I live on the 4th floor. Compared to my friend who lives on the 12th floor, I experience time...

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

Question 13

The general-relativistic prediction for the perihelion precession of Mercury was...

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

Question 14

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

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

Question 15

Which of the following is a stellar black hole?

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

Question 16

How did LIGO provide evidence for gravitational waves in 2015?

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

Question 17

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

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

Question 18

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.
50 seconds.
10 seconds.

Question 19

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

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

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

Question 21

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

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

Question 22

In Newtonian mechanics, the speed of light in vacuum...

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

Question 23

What is an Einstein ring?

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

Question 24

Which of the following objects bends spacetime the most?

The Earth.
The Moon.
The Sun.

Question 25

What makes the expansion of the universe accelerate?

Dark nebulae.
Dark matter.
Dark energy.