Science M.C.Q

(D) A is false but R is true.

After some time, the magnetic field gets constant; this means that there is no relative change in the value of magnetic field. Therefore, the circuit will have zero induced current.

If magnetic field lines are parallel and equidistant, they represent a uniform magnetic field.

The colour of an earth wire is generally green.

The magnetic field generated along the axis of a solenoid is proportional to the number of turns per unit length in it.

Because clockwise flow of current in a circular loop behaves like South Pole.

In other options, the strength of magnetic field can change because the strength of magnetic field produced by a solenoid depends on number of turns, current and material of the core of the electromagnet.

In Fleming's left hand rule the thumb represents the direction of force experienced by a current carrying conductor placed in an external magnetic field.

The closed curves in a magnetic field is called the magnetic lines of force.
Outside the magnets, the field lines emerge from north pole and merge at the south pole. Inside the magnet, the direction of field lines is from its south pole to its north pole. Thus the magnetic field lines are closed curves.

The core of solenoid must be of some soft type magnetic material which can be strongly magnetized but does not retain induced magnetism.

Use of electric fuse is the most important method used for protecting home appliances from short circuiting or overloading.
Generally, thin wire with low melting having specific rating is connected in series with the electric devices. When the current passing through the fuse exceeds a specific value then by heating effect of current it melts and breaks the circuit.

An electric generator is a machine that generates electricity by using the principle of electromagnetic induction. It converts mechanical energy to electrical energy.

A generator converts mechanical energy into electrical energy, while a motor does the opposite it converts electrical energy into mechanical energy. Both devices work because of electromagnetic induction, which is when a voltage is induced by a changing magnetic field.

Current induced by the process of electromagnetic induction does not depend on the resistivity of wire of the coil used.

During wiring in our houses, we use the traditional concept of using red colour wire as live, black as neutral and green for the earth.
These colour codes are used to distinguish between live, earth and neutral

Magnetic Field Pattern due to a Circular Loop Carrying Current. The magnetic field lines are concentric circles at every point of a current carrying circular loop. The direction of magnetic field at the centre of circular coil is perpendicular to the place of the coil. i.e. along the axis of the coil.

During wiring in our houses, we use the traditional concept of using red colour wire as live, black as neutral and green for earth. These colour codes are used to distinguish between live, neutral and earth. which is a standard way of colours coding for electric connections.

In an electrical motor, electrical energy is converted into mechanical energy.

Magnetic field line never intersect each other.

Electrical appliances are connected in a parallel arrangement in a house circuit because each appliance gets full voltage as resistance in a parallel arrangement is low. If one appliance fuses, it does not affect the working of other appliances. We can use one appliance without using other appliances.

A solenoid behaves like a bar magnet. Hence, the pattern of the magnetic field associated with the solenoid is same as the pattern of the magnetic field around a bar magnet.

Producing induced current in a coil due to relative motion between a magnet and the coil.

An electric generator is a device that converts mechanical energy to electrical energy using the principle of electromagnetic induction. Hence, it generates electric current for the supply of electrical power to consumers.