O-LevelPhysicsElectricity5054/22 · May/June 2021 · Q66 Marks
The power input to a filament lamp when connected to a 12V supply is 20W.
- (a)State what is meant by power.[1]
- (b)(i)the current in the filament current =[2]
- (b)(ii)the resistance of the filament. resistance =[1]
- (c)The filament in another lamp is made from thinner wire of the same length and made from the same material. Both lamps are connected to a 12V supply. State and explain how using thinner wire in the filament affects the power input to the lamp.[2]
Mark scheme
Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.
- [B1] work done / energy (transfer) per unit time
- [C1] (I =) P / V in any form numerical or algebraic
- [A1] 1.7 A
- [B1] 6.9–7.2 Ω
- [B1] resistance (of wire) is larger
- [B1] power is less and either current is smaller or P = V² / R or P = VI and V = IR
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