4.4 Wave properties 2

Question 1

When waves meet, they…

Answer 1

…pass through each other. At the point where they meet, they combine for an instant before they move apart. This is called superposition

Question 2

What is superposition

Answer 2

The combining effect of waves when they meet

Question 3

The principle of superposition states that…

Answer 3

…when two waves meet, the total displacement at a point is equal to the sum of the individual displacements at that point.

Question 4

Where a crest meets a crest, a ______ is created - the two waves ______ each other.

Answer 4

Supercrest

Reinforce

Question 5

Where a trough meets a trough, a ______ is created - the two waves ______ each other.

Answer 5

Supertrough

Reinforce

Question 6

Where a crest meets a trough of the same amplitude, the resultant displacement is ______. The two waves ______ each other ______. If they are not the same amplitude, the resultant is called a ______.

Answer 6

Zero
Cancel
Out
Minimum

Question 7

What waves are formed on a rope if two people send waves continuously from either end

Answer 7

Stationary waves

Question 8

What are nodes

Answer 8

Points of no displacement

At each node, the two sets of waves are always 180° out of phase so they cancel each other out

Question 9

What shape are the waves caused by a vibrating dipper

Answer 9

Circular

Question 10

Where are the points of cancellation in waves caused by a dipper

Answer 10

Created where a crest from one dipper meets a trough from the other dipper. These points of cancellation are seen as gaps in the wavefronts

Question 11

Where are points of reinforcement created in waves caused by a dipper

Answer 11

Where a crest from one dipper meets a crest from the other dipper or where a trough from one dipper meets a trough from the other dipper.

Question 12

What is interference

Answer 12

The idea that cancellation and reinforcement occurs at fixed positions as the waves are continuously passing through each other at constant frequency and phase difference

Question 13

______ sources of waves produce an interference pattern where they overlap, because they vibrate at the same ______ with a constant ______ ______. If the phase difference changed at random, the points of cancellation and reinforcement would move about at ______, and no ______ pattern would be seen.

Answer 13

Coherent
Frequency
Phase difference
Random
Interference

Question 14

What can a microwave transmitter and receiver be used to demonstrate?

Answer 14

Reflection
Refraction
Diffraction
Interference
Polarisation

Question 15

Testing using microwaves - method:

Answer 15

1. Place receiver in path of microwave beam from transmitter. Move receiver gradually away from transmitter. Receiver signal decreases with distance from transmitter.
2. Place metal plate between transmitter and receiver to show that microwaves cannot pass through metal.
3. Use two metal plates to make a narrow slit and show that the receiver detects microwaves that have been diffracted as they pass through the slit. Show that if the slit is made wider, less diffraction occurs
4. Use a narrow metal plate with the two plates from step 3 to make a pair of slits. Direct transmitter at these and use receiver to find points of cancellation and reinforcement, where the microwaves from the two slits overlap.