A charge of 18 C flows through a torch bulb in 6 s. What is the current in the bulb?

Answer: B. Step 1: Recall the relationship between current and charge Current is the rate of flow of charge: I = Q/t Step 2: Substitute the values The charge is Q = 18 C and the time is t = 6 s: I = 18 C/6 s Step 3: Work out the current I = 3.0 A Why…

Electric Circuits and Resistance: Question 1

Syllabus 4.2.2

Multiple choice Core 1 mark

A charge of $18\text{ C}$ flows through a torch bulb in $6\text{ s}$ . What is the current in the bulb?

Show worked solution Hide worked solution

Step 1: Recall the relationship between current and charge

Current is the rate of flow of charge:

$I = \frac{Q}{t}$

Step 2: Substitute the values

The charge is $Q = 18\text{ C}$ and the time is $t = 6\text{ s}$ :

$I = \frac{18\text{ C}}{6\text{ s}}$

Step 3: Work out the current

$I = 3.0\text{ A}$

Why the other options are wrong

Option	How it arises	Error
$0.33\text{ A}$	$6 \div 18$	Formula inverted (time ÷ charge)
$12\text{ A}$	$18 - 6$	Subtracted instead of dividing
$108\text{ A}$	$18 \times 6$	Multiplied instead of dividing

Final answers

Current $= \boxed{3.0\text{ A}}$ , option B