Electromagnetic Induction · Physics · AP EAPCET

The self inductance of an air-cored solenoid of length 40 cm , diameter 7 cm having 200 turns is nearly

A coil having 100 square loops each of side 10 cm is placed such that its plane is normal to a magnetic field, which is changing at a rate of $0.7 \mathrm{Ts}^{-1}$. The emf induced in the coil is

When current in a coil changes from 2 A to 5 A in time of 0.3 s , if the emf induced in the coil is 40 mv , then the self inductance of the coil is

A coil of resistance $200 \Omega$ is placed in a magnetic field. If the magnetic flux $\phi$ (in weber) linked with the coil varies with time ' $t$ ' (in second) as per the equation $\phi=50 t^2+4$, then the current induced in the coil at a time $t=2 \mathrm{~s}$ is

When a current of 4 mA passes through an inductor, if the flux linked with it is $32 \times 10^{-6} \mathrm{Tm}^2$, then the energy stored in the inductor is

If a wheel with 24 metallic spokes each 40 cm long is rotated with a speed of $180 \mathrm{rev} / \mathrm{min}$ in a plane normal to the horizontal component of Earth's magnetic field, the emf induced between the axle and the rim of the wheel is $E$. If the number of spokes is made 12 and the wheel is rotated with a speed of $90 \mathrm{rev} / \mathrm{min}$ in the same field, the induced emf is

A metallic disc of radius 0.3 m is rotating with a constant angular speed of $60 \mathrm{rad} \mathrm{s}^{-1}$ in a plane perpendicular to a uniform magnetic field of $5 \times 10^{-2} \mathrm{~T}$. The emf induced between a point on the rim and centre of the disc is

A coil of 45 turns and radius 4 cm is placed in a uniform magnetic field such that its plane is perpendicular to the direction of the field. If the magnetic field increases from 0 to 0.70 T at a constant rate in a time interval of 220 s , then the induced emf in the coil is

A horizontal telegraph wire of length 30 m spread east to west fell down freely from a height of 20 m . If the resistance of the wire is $40 \Omega$ and the horizontal component of the Earth's magnetic field at the place is $2 \times 10^{-5} \mathrm{~T}$, then the induced current when the wire reaches the ground is

(Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )

A metallic wire loop of side $(l) 0.1 \mathrm{~m}$ and resistance of $1 \Omega$ is moved with a constant velocity in a uniform magnetic field of $2 \mathrm{Wm}^{-2}$ as shown in the figure. The magnetic field is perpendicular to the plane of the loop. The loop is connected to a network of resistors. The velocity of loop, so as to have a steady current of 1 mA in loop is

A coil of inductance $L$ is divided into 6 equal parts. All these are connected in parallel. The resultant inductance of this combination is

A circular loop of wire of radius 14 cm is placed in magnetic field directed perpendicular to the plane of the loop. If the field decreases at a steady rate of $$0.05 \mathrm{~Ts}^{-1}$$ in some interval, then the magnitude of the emf induced in the loop is

A circular coil has 100 turns, radius 3 cm and resistance $$4 \Omega$$. This coil is co-axial with a solenoid of 200 turns/$$\mathrm{cm}$$ and diameter 4 cm . If the solenoid current is decreased from 2 A to zero in 0.04 s , then the current induced in the coil is

An AC generator consists of a coil of 100 turns and is of cross-sectional area $$3 \mathrm{~m}^2$$. It is rotating at a constant angular speed of $$60 \mathrm{~rads}^{-1}$$ in a uniform magnetic field of $$0.04 \mathrm{~T}$$. Resistance of the coil is $$360 \Omega$$. What is the maximum power dissipation in the coil?

Assertion (A) Magnetic flux is a vector quantity.

Reason (R) Value of magnetic flux can be positive negative or zero.

The induced emf cannot be produced by

Assertion (A) When plane of coil is perpendicular to magnetic field, magnetic flux linked with the coil is minimum, but induced emf is zero.

Reason (R) $$\phi=n A B \cos \theta$$ and $$e=\frac{d \phi}{d t}$$

A solenoid of length $$60 \mathrm{~cm}$$ with 15 turns per $$\mathrm{cm}$$ and area of cross-section $$4 \times 10^{-3} \mathrm{~m}^2$$ completely surrounds another co-axial solenoid of same length and area of cross-section $$2 \times 10^{-3} \mathrm{~m}^2$$ with 40 turns per $$\mathrm{cm}$$. Mutual inductance of the system is

An electric generator is based on

Assertion (A) It is more difficult to move a magnet into a coil with more loops.

Reason (R) This is because emf induced in each current loop resists the motion of the magnet.

Two inductors A and B when connected in parallel are equivalent to a single inductor of inductance 1.5 H and when connected in series are equivalent to a single inductor of inductance 8H. Find the difference in the inductances of A and B.

The law which states that a variation in an electric field causes magnetic field, is