Waves and the Electromagnetic Spectrum RQP- speed of waves in a ripple tank and in a solid

Question 1

ripple tank

apparatus setup

Answer 1

• ripple tank over white paper with a ruler down the side
• lamp above water
• wooden rod with motor attached to power supply at the end of the ripple tank

Question 2

ripple tank

step 1

Answer 2

Set up the ripple tank as shown in the diagram with about 5 cm depth of water.

Question 3

ripple tank

step 2

Answer 3

Adjust the height of the wooden rod so that it just touches the surface of the water.

Question 4

ripple tank

step 3

Answer 4

Switch on the lamp and motor and adjust until low frequency waves can be clearly observed.

Question 5

ripple tank

step 4

Answer 5

Measure the length of a number of waves then divide by the number of waves to record wavelength. It may be more practical to take a photograph of the card with the ruler and take measurements from the still picture.

Question 6

ripple tank

step 5

Answer 6

Count the number of waves passing a point in ten seconds then divide by ten to record frequency.

Question 7

ripple tank

step 6

Answer 7

Calculate the speed of the waves using: wave speed = frequency × wavelength.

Question 8

solid

apparatus setup

Answer 8

• table with a vibration generator on the left connected to a power supply
• string attached to vibration generator help up by a wooden bridge (stick)
• string hung over pulley on end of table with a mass attached to it

Question 9

solid

step 1

Answer 9

Attach a string or cord to a vibration generator and use a 200 gram (g) hanging mass and pulley to pull the string taut as shown in the diagram. Place a wooden bridge under the string near the pulley.

Question 10

solid

step 2

Answer 10

Switch on the vibration generator and adjust the wooden bridge until stationary waves can be clearly observed.

Question 11

solid

step 3

Answer 11

Measure the length of as many half wavelengths (loops) as possible, divide by the number of half wavelengths (loops). This is half the wavelength, doubling this gives the wavelength.

Question 12

solid

step 4

Answer 12

The frequency is the frequency of the power supply.

Question 13

solid

step 5

Answer 13

Calculate the speed of the waves using: wave speed = frequency × wavelength.