O-LevelPhysicsEnergy & Work5054/21 · May/June 2023 · Q88 Marks
A filament lamp is arranged above a shiny metal surface, as shown in Fig. 8.1. [Figure 8.1] A student reads in a textbook that a light-emitting diode (LED) is more efficient than a filament lamp.
- (a)(i)State what is meant by 'efficiency'.[1]
- (a)(ii)Suggest why the efficiency of a filament lamp is very low.[1]
- (b)The student considers replacing the filament lamp shown in Fig. 8.1 with an LED of the same brightness. Data about the filament lamp and a suitable LED are shown in Table 8.1. [Table 8.1] The LED emits the same amount of visible light as the filament lamp. Using this information and the data in Table 8.1, determine the efficiency of the LED.[2]
- (c)(i)By accident, the live wire touches the shiny metal surface.[2]
- (c)(ii)In another similar lamp, the fuse is wrongly connected into the earth wire. Explain why a person is not protected when the live wire touches the shiny metal surface.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.
- [B1] useful energy output / (total) energy input
- [B1] heat / thermal energy is produced or energy is wasted
- [C1] (useful output power =) 120 × 0.062 ; 7.4 (4 W)
- [A1] 50% or 0.50
- [B2] current flows to earth / ground
- fuse blows/melts
- stops current/ breaks the circuit/not live
- [B2] fuse (still) melts
- lamp appears off
- metal case still live / can cause electrocution or shock
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →