1.

A carbon resistor is coloured with four different bandsred, green, orange and silver respectively. Find the range of its probable resistance. Or, EMF of an electrical cell is 2 volt. A 10Omega resistance is joined at its two ends then potential difference is measured 1.6 volt. Find out the internal resistance and lost volt.

Answer»

Solution :Red : 2, GREEN : 5, orange:3,zeroes, silver: 10% error
`therefore` RESISTANCE = 25000`pm 10% Omega`
` 10% of 25000 Omega = 2500Omega`
`therefore`Range of the resistance
= (25000 - 2500) to (25000 + 2500)
=22500`Omega` to 27500`Omega`
Or,
LOST VOLT = 2 - 1.6 = 0.4 V
Current through this circuit , `I = (1.6 V)/(10Omega) = 0.16 A`
Internal resistance, `r = (Ir)/(I) = (" lost volt")/(I) = (0.4V)/(0.16 A) = 2.5 Omega`


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