Standard Grade Physics Telecommunication

1. Why can you see lightning before you hear thunder?

Because lightning happens first

Because of magic

Because the speed of light is faster than the speed of sound

Because you are slighty deaf

All of the above

The correct answer is "Because the speed of light is faster than the speed of sound." When lightning occurs, it emits light which travels at a speed of approximately 299,792 kilometers per second. Sound, on the other hand, travels at a much slower speed of about 343 meters per second. As a result, the light from the lightning reaches our eyes almost instantly, while the sound takes some time to travel to our ears. This is why we see the lightning before we hear the thunder.

Explanation

The correct answer is "Because the speed of light is faster than the speed of sound." When lightning occurs, it emits light which travels at a speed of approximately 299,792 kilometers per second. Sound, on the other hand, travels at a much slower speed of about 343 meters per second. As a result, the light from the lightning reaches our eyes almost instantly, while the sound takes some time to travel to our ears. This is why we see the lightning before we hear the thunder.

2. What symbol represents wavelength?

π

Σ

λ

ν

D

The symbol λ represents wavelength. In physics, wavelength is the distance between two consecutive points in a wave that are in phase. It is usually represented by the Greek letter lambda (λ). The symbol π represents the mathematical constant pi, Σ represents the summation symbol, ν represents frequency, and d is a generic symbol that could represent various quantities.

Explanation

The symbol λ represents wavelength. In physics, wavelength is the distance between two consecutive points in a wave that are in phase. It is usually represented by the Greek letter lambda (λ). The symbol π represents the mathematical constant pi, Σ represents the summation symbol, ν represents frequency, and d is a generic symbol that could represent various quantities.

3. A wave machine creates 45 waves per minute in a swimming pool. The waves are 2.25 metres long. What is the freqency of the waves?

10 Hz

20 Hz

30 Hz

40 Hz

50 Hz

The frequency of a wave is the number of waves that occur in one second. In this question, it is stated that the wave machine creates 45 waves per minute. To find the frequency, we need to convert minutes to seconds. There are 60 seconds in one minute, so the wave machine creates 45 waves in 60 seconds. Dividing 45 by 60 gives us the frequency of 0.75 waves per second. However, the question asks for the frequency in Hz, which is cycles per second. Therefore, we multiply 0.75 by 2 to get the frequency of 1.5 Hz. Since none of the given options match this frequency, the correct answer is not provided.

Explanation

The frequency of a wave is the number of waves that occur in one second. In this question, it is stated that the wave machine creates 45 waves per minute. To find the frequency, we need to convert minutes to seconds. There are 60 seconds in one minute, so the wave machine creates 45 waves in 60 seconds. Dividing 45 by 60 gives us the frequency of 0.75 waves per second. However, the question asks for the frequency in Hz, which is cycles per second. Therefore, we multiply 0.75 by 2 to get the frequency of 1.5 Hz. Since none of the given options match this frequency, the correct answer is not provided.

4. A wave with a freqency of 4500 Hz has a length of 3.5cm. What speed is it travelling at?

275.5 m/s

23.4 m/s

157.5 m/s

10923 m/s

89.06 m/s

The speed of a wave can be calculated by multiplying its frequency by its wavelength. In this case, the given wave has a frequency of 4500 Hz and a wavelength of 3.5 cm. By multiplying these values together, we get a speed of 157.5 m/s.

Explanation

The speed of a wave can be calculated by multiplying its frequency by its wavelength. In this case, the given wave has a frequency of 4500 Hz and a wavelength of 3.5 cm. By multiplying these values together, we get a speed of 157.5 m/s.

5. When a wave travels, what does it carry from place to place?

Copper

Signals

Electricity

Energy

UHF

When a wave travels, it carries energy from one place to another. This energy can take different forms depending on the type of wave, such as mechanical energy in the case of sound waves or electromagnetic energy in the case of light waves. Regardless of the specific type of wave, energy is the fundamental quantity that is transferred as the wave propagates through space.

Explanation

When a wave travels, it carries energy from one place to another. This energy can take different forms depending on the type of wave, such as mechanical energy in the case of sound waves or electromagnetic energy in the case of light waves. Regardless of the specific type of wave, energy is the fundamental quantity that is transferred as the wave propagates through space.

6. What is the period of a wave with a freqency of 34 Hz?

0.103s

1.031s

0.03s

0.1213s

0.893s

The period of a wave is the time it takes for one complete cycle to occur. It is inversely proportional to the frequency of the wave. In this case, the frequency is given as 34 Hz. To find the period, we can use the formula: period = 1/frequency. Plugging in the given frequency, we get: period = 1/34 = 0.03s. Therefore, the correct answer is 0.03s.

Explanation

The period of a wave is the time it takes for one complete cycle to occur. It is inversely proportional to the frequency of the wave. In this case, the frequency is given as 34 Hz. To find the period, we can use the formula: period = 1/frequency. Plugging in the given frequency, we get: period = 1/34 = 0.03s. Therefore, the correct answer is 0.03s.