Two point charges of 10 C each are kept at a distance of 3 m in vacuum.Calculate their electrostatic potential energy.

Four capacitors C_1, C₂, C₃ and C₄ are connected as shown in the figure below. Calculate equivalent capacitance of the circuits between points X and Y.

Draw a labelled graphs to show how electrical resistance varies with temperature for:
i) a metallic wire
ii) a piece of carbon

Two resistors R₁ = 400 ohm and R₂ = 20 ohm are connected in parallel to a battery. If heating power developed in R₁ is 25 W, find the heating power developed in R₂.

With the help of a labelled diagram, show that the balancing condition of a wheatstone bridge is:


; have their usual meanings.

A 10 m long uniform metallic wire having a resistance 20 ohm is used as a potentiometer wire. This wire is connected in series with another resistance of 480 ohm and a battery of emf 5 V having negligible internal resistance.If an unknown emf e is balanced across 6 m of the potentiometer wire, calculate:

i) the potential gradient across the potentiometer wire.
ii) the value of the unknown emf e.

i) Explain the term hysteresis.

ii) Name the three elements of the earth's magnetic field which help in defining earth's magnetic field completely.

28.

Obtain an expression for magnetic flux density B at the centre of a circular coil of radius R, having N turns and carrying a current I.

A coil of self inuctance 2.5 H and resistance 20 ohm is connected to a battery of emf 120 V having internal resistance of 5 ohm. Find:

i) the time constant of the circuit

ii) the current in the circuit in steady state.

In a series LCR circuit, what is the difference between V_L and V_C where v_L is the potential difference across the inductor and V_Cis the potential difference across the capacitor.