Why can you see lightning before you hear thunder?

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

Because lightning happens first

Standard Grade Physics TELECOMMUNICATION

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Quizzes Created: 2 | Total Attempts: 1,515

Questions: 6 | Attempts: 989 | Updated: Oct 18, 2024

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Standard Grade Physics Telecommunication - Quiz

A quiz for people studying physics at standard grade level

Questions and Answers

1.

When a wave travels, what does it carry from place to place?
- A.
  
  Copper
- B.
  
  Signals
- C.
  
  Electricity
- D.
  
  Energy
- E.
  
  UHF
Correct Answer
D. Energy

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.

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2.

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?
- A.
  
  10 Hz
- B.
  
  20 Hz
- C.
  
  30 Hz
- D.
  
  40 Hz
- E.
  
  50 Hz
Correct Answer
B. 20 Hz

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.

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1
0
3.

What symbol represents wavelength?
- A.
  
  π
- B.
  
  Σ
- C.
  
  λ
- D.
  
  ν
- E.
  
  D
Correct Answer
C. λ

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.

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4.

Why can you see lightning before you hear thunder?
- A.
  
  Because lightning happens first
- B.
  
  Because of magic
- C.
  
  Because the speed of light is faster than the speed of sound
- D.
  
  Because you are slighty deaf
- E.
  
  All of the above
Correct Answer
C. Because the speed of light is faster than the speed of sound

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.

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5.

What is the period of a wave with a freqency of 34 Hz?
- A.
  
  0.103s
- B.
  
  1.031s
- C.
  
  0.03s
- D.
  
  0.1213s
- E.
  
  0.893s
Correct Answer
C. 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.

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6.

A wave with a freqency of 4500 Hz has a length of 3.5cm. What speed is it travelling at?
- A.
  
  275.5 m/s
- B.
  
  23.4 m/s
- C.
  
  157.5 m/s
- D.
  
  10923 m/s
- E.
  
  89.06 m/s
Correct Answer
C. 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.

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Current Version
Oct 18, 2024

Quiz Edited by
ProProfs Editorial Team
Mar 14, 2009

Quiz Created by
Bhsobserver

Standard Grade Physics Telecommunication

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

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?

What symbol represents wavelength?

Why can you see lightning before you hear thunder?

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

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