CBSE Class 10 Science 2019 · Paper 31/3/1 · Question 27

Electricity 2 marks Medium

Consider the scale of a voltmeter shown in the diagram and answer the following questions :

(a)What is the least count of the voltmeter ?
(b)What is the reading shown by the voltmeter ?
(c)If this voltmeter is connected across a resistor of $20 Ω$ , how much current is flowing through the resistor ?

Answer

The least count is 0.15 V, the reading is 1.8 V and the current through the $20 Ω$ resistor is 0.09 A.

(a) Least count

= \frac{1.5 V}{10} = 0.15

V (10 divisions between the marks 0 and 1.5). (b) The pointer is 2 divisions beyond

1.5

V: reading

= 1.5 + 2 \times 0.15 = 1.8

V. (c)

I = \frac{V}{R} = \frac{1.8 V}{20 Ω} = 0.09

🔒 Step-by-step solution