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Moving Charges And Magnetism

Question
CBSEENPH12039705
Wired Faculty App

The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?

  • 40 Ω

  • 20 Ω

  • 400 Ω

  • 200 Ω

Solution

A.

40 Ω

straight R subscript hot space equals space straight V squared over straight P space equals space fraction numerator 200 space straight x space 200 over denominator 100 end fraction space equals space 400 space straight capital omega Cold space resistance space equals space straight R subscript hot divided by 10 space equals space 400 divided by 10 space equals space 40 space straight capital omega space

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.

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