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NEET - Physics Current Electricity Test Yourself

23488.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
1.6 × 10–8 Ωm
1.6 × 10–7 Ωm
1.6 × 10–6 Ωm
1.6 × 10–5 Ωm
23489.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
flow from Antimony to Bismuth at the cold junction
flow from Antimony to Bismuth at the hot junction
flow from Bismuth to Antimony at the cold junction
not flow through the thermocouple
23490.The length of a given cylindrical wire is increased by 100 %. Due to the consequent decrease in diameter the change in the resistance of the wire will be
300 %
200%
100 %
50%
23491.A 5V battery with internal resistance 2 Ω and a 2V battery with internal resistance 1 Ω are connected to a 10 Ω resistor as shown in the figure.
5V battery with internal resistance
The current in the 10 Ω resistor is
0.03 A P1 to P2
0.03 A P2 to P1
0.27 A P1 to P2
0.27 A P2 to P1
23492.In a metre bridge experiment, null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y.If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y?
50 cm
80 cm
40 cm
70 cm
23493.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.
1 A
1.5 A
2 A
5 A
23494.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
23495.The temperature dependence of resistances of Cu and undoped Si in the temperature range 300–400 K, is best described by
Linear increase for Cu, exponential increase for Si
Linear increase for Cu, exponential decrease for Si
Linear decrease for Cu, linear decrease for Si
Linear increase for Cu, linear increase for Si
23496.A circuit contains an ammeter, a battery of 30 V and a resistance 40.8 ohm all connected in series. If the ammeter has a coil of resistance 480 ohm and a shunt of 20 ohm, the reading in the ammeter will be
1 A
0.5 A
0.25 A
2 A
23497.A material ‘B’ has twice the specific resistance of ‘A’. A circular wire made of ‘B’ has twice the diameter of a wire made of ‘A’. Then for the two wires to have the same resistance, the ratio $l$A / $l$B of their respective lengths must be
1
2
1/2
1/4
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