### All High School Physics Resources

## Example Questions

### Example Question #1 : Waves

Two waves, each with an amplitude of are superimposed with constructive interference such that they are in phase. What is the resultant amplitude?

**Possible Answers:**

**Correct answer:**

When two waves are superimposed, the interference can either be constructive or destructive. In this case, the interference is constructive and the waves are in phase, which means we add the amplitudes together.

Since each wave has an amplitude of , our new amplitude will be .

### Example Question #1 : Waves

Two waves, one with an amplitude of and the other of are superimposed with destructive interference. What is the resultant amplitude?

**Possible Answers:**

**Correct answer:**

When two waves are superimposed, the interference can be either constructive or destructive. In this case the interference is destructive, which means our resultant amplitude will be the difference of the two given amplitudes.

That means our new amplitude will be .

### Example Question #1 : Waves, Sound, And Light

Two identical waves are superimposed with destructive interference. What will happen to the resulting wave?

**Possible Answers:**

It will be still. There will be no wave.

It will be twice as large as each original wave.

It will be half as large as each original wave.

The two waves will pass through each other without problem.

**Correct answer:**

It will be still. There will be no wave.

When two waves are superimposed with destructive interference, they cancel each other out. Since these two waves are identical, they will completely cancel each other out and there will be no wave. It will be still.

### Example Question #1 : Understanding Wavelength And Frequency

After exercising, Jane takes her pulse. She realizes that her heart is beating rapidly, approximate four beats every second. What is the period of her elevated heart rate?

**Possible Answers:**

**Correct answer:**

When you see a relationship like "times every second" or "once per hour," these are hints you are looking at a frequency. Frequency is, effectively, how often something happens. If it happens four times per second, then we know how often it happens. The units "per second" are equivalent to Hertz.

The relationship between frequency and period is .

Since our given frequency was four beats per second, or , we can solve for the period.

This means that her heart beats once every 0.25 seconds.

### Example Question #2 : Understanding Wavelength And Frequency

A radio station broadcasts at a frequency of . If the broadcast is an electromagnetic wave, then what is its wavelength?

**Possible Answers:**

**Correct answer:**

The relationship between wavelength and frequency is given by the equation , where is the wavelength, is the speed of light, and is frequency.

We are given the values for frequency and the speed of light, allowing us to solve for the wavelength.

### Example Question #1 : Waves, Sound, And Light

A wave oscillates with a speed of and has a wavelength of . What is the frequency of the wave?

**Possible Answers:**

**Correct answer:**

The equation for velocity in terms of wavelength and frequency is .

We are given the velocity and the wavelength. Using these values, we can solve for the frequency.

### Example Question #1 : Understanding Wavelength And Frequency

A symphony tunes to an oboe playing a note at . If the speed of sound is , what is the wavelength of this note?

**Possible Answers:**

**Correct answer:**

The relationship between velocity, frequency, and wavelength is:

Plug in the given information to solve:

### Example Question #1 : Understanding Wavelength And Frequency

A note is played with a wavelength of . If the speed of sound is , what is the frequency of the note?

**Possible Answers:**

**Correct answer:**

The relationship between velocity, frequency, and wavelength is:

Plug in the given information to solve:

### Example Question #1 : Waves

A wave has a frequency of . What is its period?

**Possible Answers:**

**Correct answer:**

The relationship between frequency and period is .

Plug in our given value:

### Example Question #1 : Understanding Wavelength And Frequency

A wave with a constant velocity doubles its frequency. What happens to its wavelength?

**Possible Answers:**

The new wavelength will be the old wavelength.

There is insufficient information to solve.

The new wavelength will also double.

The wavelengths will be the same.

**Correct answer:**

The new wavelength will be the old wavelength.

The relationship between velocity, frequency, and wavelength is:

In this case we're given a scenario where and . The velocities equal each other because the problem states it has a constant velocity. Therefore we can set these equations equal to each other:

Notice that the 's cancel out:

Divide both sides by two: