4th grade light, sound and waves

Question 1

In a long spring (slinky) on the floor, 6 complete waves fit into 30 cm. What is the wavelength?

Answer cm

Question 2

In Morse code, TREE is sent as – / •–• / • / •. How many flashes (dots and dashes) is that altogether?

Answer 

Question 3

Pitch and loudness: which statement is NOT true?

• A. Pitch is how high or low a sound is.
• B. Faster vibrations make higher-pitched sounds.
• C. Humans can hear sounds from about 20 Hz to 20 000 Hz.
• D. Loud sounds always have a high pitch.

Question 4

Phones and computers send pictures and music as patterns of just two signals, like on and off. What is this called?

• A. a rainbow
• B. digital information
• C. an echo
• D. a shadow

Question 5

Ocean waves can turn machines that make electricity. What are they using?

• A. the salt in the water
• B. the energy the waves carry
• C. the colour of the sea
• D. fish swimming past

Question 6

Which drum makes the lowest sound?

• A. a small drum with a tight skin
• B. a tiny drum
• C. a big drum with a loose skin
• D. a drum with a very tight skin

Question 7

True or false? The trough is the highest point of a wave.

• A. True
• B. False

Question 8

Pitch and loudness: which statement is true?

• A. Loud sounds always have a high pitch.
• B. Hitting a drum harder makes a higher note.
• C. Pitch is how high or low a sound is.
• D. Longer strings make higher notes.

Question 9

Which word means the distance from one crest to the next crest?

• A. trough
• B. amplitude
• C. wavelength
• D. crest (peak)

Question 10

Can sound travel through this: a wooden table?

• A. sound can travel through it
• B. sound cannot travel through it

Question 11

Put your ear on a table while a friend taps the far end gently. Why do you hear it clearly?

• A. Sound travels well through solids.
• B. Your ear makes the sound.
• C. Sound cannot travel through air.
• D. Tables make sounds louder by magic.

Question 12

Waves and energy: which statement is true?

• A. A wave can travel without any energy.
• B. A wave in a rope moves along while each bit of rope moves up and down.
• C. Ripples on a pond carry the stone to the edge.
• D. Surfers are carried by water travelling across the whole ocean.

Question 13

True or false? Bigger waves carry less energy.

• A. True
• B. False

Question 14

True or false? Sound travels faster than light.

• A. True
• B. False

Question 15

A torch (flashlight) flashes short (•) and long (–) pulses. Use the key to decode the message. Key: M = –– O = ––– N = –• Message: –– / ––– / ––– / –•

Answer 

Question 16

What is the job of the lens?

• A. the hole that lets light into the eye
• B. protects the eye and spreads tears
• C. focuses light onto the back of the eye
• D. the coloured ring that makes the pupil bigger or smaller