Current Electricity MCQs (NEET, JEE Main) – Test 4

In balanced metre bridge, the resistance of bridge wire is 0.1 Ω / cm. Unknown resistance ‘X’ is connected in left gap and 6 Ω  in right gap, null point divides the wire in the ratio 2 : 3. Find the current drawn from the battery of 5 V having negligible resistance. [MHT CET 2016]

A potentiometer wire has length 4 m and resistance 8 Ω. The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2 V, so as to get a potential gradient 1 mV per cm on the wire is [CBSE AIPMT 2015]

When 5 V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is 2.5 × 10^–4 ms^–1.
If the electron density in the wire is 8 × 10²⁸ m^–3, the resistivity of the material is close to [JEE Main 2015]

Shown in the figure below is a meter-bridge set up with null deflection in the galvanometer. [AIEEE 2008]

The value of the unknown resistor R is

A thermocouple is made from two metals, Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold then, an electric current will [AIEEE 2006]