When 5V 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 x 10^-8Ωm

• 1.6 x 10^-7Ωm

• 1.6 x 10^-6Ωm

• 1.6 x 10^-6Ωm

In the circuit shown, the current in the 1Ω resistor is:

• 1.3 A from P to Q

• 0 A

• 0.13 A, from Q to P

• 0.13 A, from P to Q

Two long current carrying thin wires, both with current I, are held by insulating threads of length L and are in equilibrium as shown in the figure, with threads making an angle ‘θ’ with the vertical. If wires have mass λ per unit length then the value of I is: (g = gravitational acceleration)

An inductor (L = 0.03 H) and a resistor (R = 0.15 kΩ) are connected in series to a battery of 15V EMF in a circuit shown. The key K₁ has been kept closed for a long time. Then at t = 0, K₁ is opened and key K₂ is closed simultaneously. At t = 1 ms, the current in the circuit will be:
()

• 100 mA

• 67 mA

• 6.7 mA

• 6.7 mA

5.

The current voltage relation of the diode is given by I = e(1000V/T-1) mA, where the applied voltage V is in volt and the temperature T is in kelvin. If a student makes an error measuring ± 0.01V while measuring the current of 5mA at 300K, what will be the error in the value of current in mA?

• 0.2 mA

• 0.02 mA

• 05 mA

• 05 mA

The coercivity of a small magnet where the ferromagnet gets demagnetized is 3 x 10³Am^-1.The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is

• 30 mA

• 60 mA

• 3 A

• 3 A

In the circuit shown here, the point C is kept connected to point A till the current flowing through the circuit becomes constant. Afterwards, suddenly point C is disconnected from point A and connected to point B at time t= 0. Ratio of the voltage across resistance and the inductor at t = L/R will be equal to 

• 

• 1

• -1

• -1

The supply voltage to a room is 120 V. The resistance of the lead wires is 6 Ω. A 60 W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240 W heater is switched on in parallel to the bulb?

• zero

• 2.9V

• 13.3 V

• 13.3 V

This question has statement I and statement II. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement- I: Higher the range, greater is the resistance of ammeter.
Statement- II: To increase the range of ammeter, additional shunt needs to be used across it.

• Statement – I is true, Statement – II is true, Statement – II is the correct explanation of statement- I.

• Statement – I is true, Statement – II is true, Statement – II is not the correct explanation of Statement–I.

• Statement – I is true, statement – II is false.

• Statement – I is true, statement – II is false.

The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is :

• 3 V/m

• 6 V/m

• 9 V/m

• 9 V/m