CBSE Class 10 Science 2019 · Paper 31/5/1 · Question 25(a)

Electricity 2 marks Medium

The rest position of the needles in a milliammeter and voltmeter, not in use, are as shown in Figure A. When a student uses these instruments in his experiment, the readings of the needles are in the positions shown in Figure B. Determine the correct values of current and voltage the student should use in his calculations.

Answer

The correct values are current 38 mA and voltage 3.2 V.

Current

= 38

mA and voltage

= 3.2

V. Least counts: milliammeter

10 \div 5 = 2

mA per division; voltmeter

1 \div 5 = 0.2

V per division. Zero errors (Figure A): the milliammeter needle rests 2 divisions to the left of zero,

- 4

mA; the voltmeter needle rests 2 divisions to the right of zero,

+ 0.4

V. Readings (Figure B):

34

mA and

3.6

V. Correct values (reading minus zero error):

I = 34 - (- 4) = 38

mA;

V = 3.6 - 0.4 = 3.2

🔒 Step-by-step solution

CBSE Class 10 Science 2019 · Paper 31/5/1 · Question 25(a)

Answer

From the board papers

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