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Moving Charges And Magnetism
Question
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To reduce the range of voltmeter, its resistance needs to be reduced. A voltmeter has resistance Ro and ranges V. Which of the following resistances when connected in parallel will convert it into a voltmeter of range V/n?

  • nR0

  • (n+1)R0

  • (n-1)R

  • None of these

Answer

D.

None of these

When a resistance is connected in parallel, it reduces the resistance of combination but the range is not reduced. For the purpose of reducing the range the resistance in series with galvanometer need to be reduced.

This cannot be achieved by connecting a resistance in parallel with a voltmeter. It should be noted that the range of voltmeter can only be increased but cannot be decreased.

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Some More Questions From Moving Charges And Magnetism Chapter

Two moving coil meters, M1 and M2 have the following particulars:
R1 = 10 Ω   N1 = 30,
A1 = 3.6 x 10–3 m2,  B1 = 0.25 T
R2 = 14 Ω;  N2 = 42,
A2 = 1.8 x 10–3 m2, B2 = 0.50 T
(The spring constants k are identical for the two meters).
Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of M2 and M1.

Answer the following questions:
A charged particle enters an environment of a strong and non-uniform magnetic field varying from point to point both in magnitude and direction, and comes out of it following a complicated trajectory. Would its final speed equal the initial speed if it suffered no collisions with the environment?