Unit Test — Cumulative exam Answers

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A charged particle moves at 2.5 × 104 m/s at an angle of 25° to a magnetic field that has a field strength of 8.1 × 10–2 T.

3.7 × 10–5 C

4.1 × 10–5 C

8.8 × 10–5 C

1.0 × 10–4 C

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What best explains why a person can become sunburned by spending too much time at the beach?

Sunlight is an electromagnetic wave that gains energy as it travels through air to reach the person.

Sunlight is an electromagnetic wave carrying energy that is absorbed by the skin.

Sunlight is a mechanical wave that vibrates the skin particles to produce heat.

Sunlight is a mechanical wave, and its frequency matches the natural frequency of skin to make heat.

Seven-eighths of a sample of hydrogen-3 will have become a stable isotope after 36.9 years. What is the half-life of hydrogen-3?

12.3 years

18.5 years

32.3 years

36.9 years

What is the purpose of the metal core in an electromagnet?

It is magnetized and induces a current in the solenoid to decrease the magnetic field strength.

It is magnetized and induces a current in the solenoid to increase the magnetic field strength.

It is magnetized by the field of the solenoid and increases the magnetic field strength.

It is magnetized by the field of the solenoid and decreases the magnetic field strength.

What is the main difference between a longitudinal wave and a transverse wave?

A longitudinal wave always travels faster than a transverse wave.

A longitudinal wave does not need a medium to travel through.

A transverse wave is made of particles that move perpendicular to the motion of the wave.

A transverse wave always carries more energy so that it can travel through empty space.

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