Conservation and dissipation of energy

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Question 1
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A student has a smart backpack equipped with a miniature solar panel to power a built-in display screen.

a.

Which equation links current (III), potential difference (VVV), and power (PPP)?

  • Choice A: P=VIP = \frac{V}{I}P=IV​
  • Choice B: P=V×IP = V \times IP=V×I
  • Choice C: I=P×VI = P \times VI=P×V
  • Choice D: V=I2×PV = I^2 \times PV=I2×P
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b.

When the solar panel is in sunlight, it generates a potential difference of 15 V15\text{ V}15 V. The power output of the solar panel is 4.5 W4.5\text{ W}4.5 W. Calculate the current in the solar panel.

[2]
c.

Which equation links efficiency, total power input, and useful power output?

  • Choice A: Efficiency\text{Efficiency}Efficiency = useful power outputtotal power input\frac{\text{useful power output}}{\text{total power input}}total power inputuseful power output​
  • Choice B: Efficiency\text{Efficiency}Efficiency = total power inputuseful power output\frac{\text{total power input}}{\text{useful power output}}useful power outputtotal power input​
  • Choice C: Efficiency\text{Efficiency}Efficiency = useful power output\text{useful power output}useful power output ×\times× total power input\text{total power input}total power input
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d.

The solar panel powers a display screen. The display screen has a total power input of 2.5 W2.5\text{ W}2.5 W. The efficiency of the display screen is 0.840.840.84. Calculate the useful power output of the display screen.

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Conservation and dissipation of energy Questions

  1. GCSE
  2. /Physics
  3. /Conservation and dissipation of energy