The resistance of a given wire is obtained by measuring the current flowing in it and the voltage difference applied across it. If the percentage errors in the measurement of the current and the voltage difference are 3% each, then error in the value of resistance of the wire is

• 6%

• zero

• 1%

• 1%

Two electric bulbs marked 25W – 220V and 100W – 220V are connected in series to a 440Vsupply. Which of the bulbs will fuse?

• Both

• 100 W

• 25 W

• 25 W

If a wire is stretched to make it 0.1% longer, its resistance will

• increase by 0.2%

• decreases by 0.2%

• decrease by 0.05 %

• decrease by 0.05 %

A rectangular loop has a sliding connector PQ of length

In the circuit shown below, the key K is closed at t = 0. The current through the battery is

Which of the following statements is false?

• A rheostat can be used as a potential divider

• Kirchhoff's second law represents energy conservation

• Wheatstone bridge is the most sensitive when all the four resistances are of the same order of magnitude.

• Wheatstone bridge is the most sensitive when all the four resistances are of the same order of magnitude.

When a current of 5 mA is passed through a galvanometer having a coil of resistance 15Ω, it shows full-scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into to voltmeter of range 0 – 10 V is

• 2.535 × 10³ Ω

• 4.005 × 10³ Ω

• 1.985 × 10³ Ω

• 1.985 × 10³ Ω

In the above circuit the current in each resistance is

• 0.5 A

• 0 A

• 0.25

• 0.25

19.

This question contains Statement-1 and Statement-2. Of the four choices given after the statements,choose the one that best describes the two statements.

Statement-1: The temperature dependence of resistance is usually given as R = R_o(1 + α∆t). The resistance of a wire changes from 100 Ω to 150 Ω when its temperature is increased from 27^o C to 227^o C. This implies that 3^o 2.5 10 / C − α= ×.
Statement 2: R = Ri(1 + α∆T) is valid only when the change in the temperature ∆T is small and ∆R =(R - R_o) << R_o.

• Statement-1 is true, Statement-2 is false.

• Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-1.

• Statement-1 is true, Statement-2 is true; Statement-2 is not the correct explanation of Statement-1.

• Statement-1 is true, Statement-2 is true; Statement-2 is not the correct explanation of Statement-1.

Shown in the figure below is a meter-bridge set up with null deflection in the galvanometer.

The value of the unknown resistor R is

• 13.75 Ω

• 220 Ω

• 110 Ω

• 110 Ω