Current Electricity: NEET questions with solutions

NEET tests this chapter through drift velocity, resistance changes (stretching, temperature), cells with internal resistance, cell combinations, Kirchhoff's rules and the Wheatstone bridge, plus power in series/parallel loads. Marks are lost on unit conversions (mm² to m²), on sign errors in loop equations, and on assuming a bridge is balanced without checking the ratio.

1. 1.A copper wire of uniform cross-sectional area 2.5 mm² carries a steady current of 4.0 A. The number density of free electrons in copper is…Drift of electrons and the origin of resistivityEasySingle correct
2. 2.A uniform metal wire has a resistance of 8.0 Ω. It is drawn out uniformly so that its length becomes 25% greater than before, with its…Ohm's law and resistivityEasySingle correct
3. 3.A coil of metal wire has a resistance of 20.0 Ω at 20 °C. The temperature coefficient of resistivity of the metal (taking 20 °C as the…Temperature dependence of resistivityEasySingle correct
4. 4.A cell of unknown emf E and internal resistance r is connected in series with an ideal ammeter and a 5.0 Ω resistor; the ammeter reads 0.50…Cells, emf, internal resistanceMediumSingle correct
5. 5.Four resistors are joined to form a closed quadrilateral ABCD: 2 Ω between A and B, 4 Ω between B and C, 6 Ω between C and D, and 3 Ω…Wheatstone bridgeMediumSingle correct
6. 6.Two cells are connected in parallel: their positive terminals are joined to one junction and their negative terminals to another. Cell 1 has…Cells in series and in parallelHardSingle correct
7. 7.Bulb P is rated 100 W, 200 V and bulb Q is rated 25 W, 200 V. The two bulbs are connected in series across a 200 V supply. Assuming each…Electrical energy, powerMediumSingle correct
8. 8.Read the Assertion (A) and Reason (R) about a copper wire whose cross-section tapers steadily from 2 mm² at one end to 1 mm² at the other…Electric currents in conductorsMediumAssertion–Reason
9. 9.An ideal 12 V battery (no internal resistance) has its positive terminal connected to junction A and its negative terminal to junction C.…Kirchhoff's rulesHardSingle correct