Formative Practice 7.2 – Science Form 2 Chapter 7

Question 1:
Draw a parallel circuit using three bulbs, a dry cell, a switch and several connecting wires.

Answer:

Question 2:


Based on Figure 1, calculate:
(a) the effective resistance
(b) the current in the circuit
(c) the voltage across each resistor

Answer:
(a)
R = 1 Ω + 3 Ω + 5 Ω
    = 9 Ω

(b)
\(I=\frac{9 \mathrm{~V}}{9 \Omega}=1 \mathrm{~A}\)

(c)
1 Ω Resistor
V = 1 A x 1 Ω
   = 1 V

3 Ω Resistor
= 1 A x 3 Ω
= 3 V

5 Ω Resistor
V = 1 A x 5 Ω
= 5 V

Question 3:


Based on Figure 2, calculate:
(a) the effective resistance
(b) the voltage
(c) the current flowing through each resistor

Answer:
(a) R = 2 Ω

(b) V = 4 V

(c)
Current in 3 Ω Resistor
\(\begin{aligned} I & =\frac{4 \mathrm{~V}}{3 \Omega} \\ & =1.3 \mathrm{~A}\end{aligned}\)

Current in 6 Ω Resistor
\(\begin{aligned} I & =\frac{4 \mathrm{~V}}{6 \Omega} \\ & =0.67 \mathrm{~A}\end{aligned}\)