(a) State Fleming's left Hand Rule.
(b)List three characteristic features of the electric current used in our homes.
(c) What is a fuse ? why is it called a safety device ?

(a) State Fleming's left hand rule. (b) Write the principle of working of an electric motor. (c ) Explain the function of the following parts of an electric motor. (i) Armature , (ii) Brushes , (iii) Split ring

Water is a universal solvent. But alcohol also dissolves most of the substances soluble in water. Boiling point of water is 100^(@)C and that of alcohol is 80^(@)C . The specific heat of water is much higher than the specific heat of alcohol. (a) List out three possible differences if instead of water as the liquid in our body we had alcohol. (b) What value can you derive from this special property of water and its innumerable uses in sustaining life on earth?

A currrent I is passed through a silver strip of width d and area of cross section A. The number of free electrons per unit volume is n. (a) Find the drift velocity v of the electrons. (b) If a magnetic field B exists in the region as shown in what is the average magnetic force on the free electrons? (c) Due to the magnetic force, the free electrons get accumulated on one side of the conductor along its length. This produces a transverse electric field in the conductor which opposes the magnetic force on the electrons. Find the magnitude of the electric field which will be the potential diference developed across the width of the conductor due to the electron- accumulation? The appearance of a transverse emf, when a current-carrying wire is placed in a magnetic field, is called hall effect.

(a) List the factors on which the resistance of a conductor in the shape of the wire depend. (b) Why are metals good conductors of electricity whereas glass is a bad conductor of electricity ? Give reason . (c ) Why are alloys commonly used in eletrical heating devices ? Give reason.

The device used for producing electric current is called a: (a) generator. (b) galvanometer. (c) ammeter. (d) motor.

Explain the following : (a) Why is tungsten used almost exclusively for filament of incandescent lamp ? (b) Why are the conductors of electric heating devices, such as toaster and electric irons, made of an alloy rather than a pure metal ? ( c) Why is the series arrangement not used for domestic circuits ? (d) How does the resistance of a wire vary with its cross-sectional area ? (e ) Why are copper and aluminium wires usually employed for electricity transmission.

The teachers of Geeta's school took the students on a study tirp to a power generating station, loactad nearly 200km away form the city.The teacher explained that electrical energy is transmitted over such a long distance to their city, in the form of alternating current (ac) raised to a high voltage. At the receiving end is the city, the voltage is reduced to operate the devices. As a result, the power loss is reduced. Geeta listened to the teacher and asked question about how the ac is converted to a higher or lower voltage. (a) Name th device used to change the alternating to a higher or lower value. State one cause for power dissipation in this device. (b) Explain with an example, how power loss is reduced if the energy is transmitted over long distance as an alternating current rather than a direct current, (c) Write two values each shown by the teachers and Geeta.

(a) Draw magnetic field lines of a bar magnet. "Two magnetic field lines never intersect each other." Why ? (b) An electric oven of 1.5 kW is operated in a dometic circuit (220V) that has a current rating of 5A. What result do you expect in this case ? Explain . or Which is meant by resistance of a conductor ? Name and define its SI units. List the factors on which the resistance of a conductor depends. How is the resistance of a wire affected if - (i) its length is doubled , (ii) its radius is doubled ?

A metal rod OA of mann 'm' and length 'r' is kept rotating with a constantangular speed omega in a vertical plane about a horizontal axis at the end O. The free end A is arraged to slide without friction along fixed conduction circular ring in the same plane as that of rotation. A uniform and constant magnetic induction vec(B) is applied perpendicular and into the plane of rotation as shown in the figure below. An inductor L and an external resistance R are connected through a swithch S between the point O and a point C on the ring to form an electrical circuit. Neglect the resistance of the ring and the rod. Initially, the switch is open. (a) What is the induced emf across the teminal of the switch? (b) The switch S is closed at time t=0. (i) Obtain an expression for the current as a function of time. (ii) In the steady state, obtin the time dependence of the torque required to maintain the constant angular speed, given that the rod OA was along th positive X-axis at t=0.