A cell can be balanced against 110 cm and 100 cm of potentiometer wire, respectively with and without being short-circuited through a resistance of 10 Ω. Its internal resistance is

• 1.0 Ω

• 0.5 Ω

• 2.0 Ω

• zero

A circular disc of radius 0.2 m is placed in a uniform magnetic field of induction in such a way that its axis makes an angle of 60^o with. The magnetic flux linked with the disc is 

• 0.02 Wb

• 0.06 Wb

• 0.05 Wb

• 0.01 Wb

A coil of resistance 400 is placed in magnetic field. If the magnetic flux Φ (Wb) linked with the coil varies with time t  (sec) as Φ = 50t² +4.
The current in the coil at t= 2 s is

• 0.5 A

• 0.1 A

• 2 A

• 1 A

A coil of self -inductance L is connected in series with a bulb b and an AC source. Brightness of the bulb decreases when

• frequency of the AC source is decreases

• number of turns in the coil is reduced

• a capacitance of reactance X_c=X_L is  included in the same circuit

• an iron is inserted in the coil

D.

an iron is inserted in the coil

A condenser of capacity C is charged to a potential difference of V₁. The plates to the condenser are then connected to an ideal inductor of inductance L. The current through the inductor when the potential difference across the condenser reduces to V₂ is

• 
• 
• 
• 

D.