# Physics-Unit 1

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## 1. Formula to calculate effieciency

• Efficiency = (useful energy out/total energy in)/100
• Efficiency = total energy in/useful energy out (*100%)
• Efficiency = useful energy out/total energy in (*100%)
• Efficiency = [useful energy out*total energy in (*100%)]
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## 2. The angle of incidence and the angle of refraction are equal when diffraction occurs?

• True they are both equal
• False, it depends on the medium
• False, the angle of reflection is smaller
• False, the angle of reflection is bigger

• Real
• Invisible
• Virtual
• Imaginary

## 4. Complete this sentence: Energy can neither be ……….. nor ………….. but it can be transferred.

• Energy can neither be created nor destroyed but it can be transferred.
• Energy can neither be lost nor destroyed but it can be transferred.
• Energy can neither be created nor lost but it can be transferred.

## 5. Complete this sentence Hotter objects emit ………… infrared radiation than cooler objects

• Hot objects do not emit emit infrared at all
• Hotter objects emit more infrared radiation than cooler objects.
• Hotter objects emit more infrared radiation than cooler objects.
• Hotter objects emit the same amount of infrared radiation than cooler objects.