During a science club, students build the low-voltage lighting circuit shown in Fig. 1 for a model house. A 12 V battery supplies two lamps in parallel. One...
Question 1 Report
During a science club, students build the low-voltage lighting circuit shown in Fig. 1 for a model house. A 12 V battery supplies two lamps in parallel. One lamp is labelled 6 W and the other is labelled 3 W. The students measure the current in the main wire before it splits. They then remove the 3 W lamp but leave the 6 W lamp switched on. The battery is not connected to mains electricity.
(a) Calculate the current in the 6 W lamp. [2]
(b) Calculate the total current before the circuit splits. [2]
(c) What happens to the 6 W lamp when the 3 W lamp is removed? [1]
Answer Details
- (a) Use \(I=\frac{P}{V}\). [1] \[ I=\frac{6\ \text{W}}{12\ \text{V}}=0.50\ \text{A} \] The current in the 6 W lamp is 0.50 A. [1]
- (b) For the 3 W lamp: \[ I=\frac{3\ \text{W}}{12\ \text{V}}=0.25\ \text{A} \] [1] In a parallel circuit, the total current is the sum of the branch currents: \[ I_{\text{total}}=0.50+0.25=0.75\ \text{A} \] [1]
- (c) The 6 W lamp stays lit with unchanged brightness. [1] It remains connected directly across the 12 V supply, so its potential difference is unchanged.
Download The App On Google Playstore
Everything you need to excel in your exams
Personalized AI Learning Chat Assistant
200,000+ Exam Questions Across IGCSE, JAMB, WAEC & NECO
Over 3,900 Lesson Notes
Offline Support - Learn Anytime, Anywhere
Green Bridge Timetable
Literature Summaries & Potential Questions
Track Your Performance & Progress
In-depth Explanations for Comprehensive Learning