Physics M.C.Q (1 Marks)

Assertion  :   Faraday’s laws are consequences of conservation of energy.
Reason      : In a purely resistive ac circuit, the current lags behind the e.m.f. in phase. (a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

A current carrying solenoid is approaching a conducting loop as shown in the figure. The direction of induced current as observed by an observer on the other side of the loop will be

Two identical coaxial circular loops carry current i each circulating in the clockwise direction. If the loops are approaching each other, then              (a) Current in each loop increases(b) Current in each loop remains the same(c) Current in each loop decreases(d) Current in one-loop increases and in the other it decreases

An inductor of 2 henry and a resistance of 10 ohms are connected in series with a battery of 5 volts. The initial rate of change of current is (a) 0.5 amp/sec(b) 2.0 amp/sec(c) 2.5 amp/sec(d) 0.25 amp/sec

Two identical circular loops of metal wire are lying on a table without touching each other. Loop-A carries a current which increases with time. In response, the loop-B(a) Remains stationary(b) Is attracted by the loop-A(c) Is repelled by the loop-A(d) Rotates about its CM, with CM fixed

If a coil made of conducting wires is rotated between poles pieces of the permanent magnet. The motion will generate a current and this device is called(a) An electric motor(b) An electric generator(c) An electromagnet (d) All of above

In a step up transformer, if ratio of turns of primary to secondary is 1 : 10 and primary voltage is 230 V. If the load current is 2A, then the current in primary is(a) 20 A   (b) 10 A(c) 2 A     (d) 1 A

A transformer with efficiency 80% works at 4 kW and 100 V. If the secondary voltage is 200 V, then the primary and secondary currents are respectively

A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be(a) Halved(b) The same(c) Doubled(d) Quadrupled

In a transformer, the number of turns in primary and secondary are 500 and 2000 respectively. If current in primary is 48 A, the current in the secondary is

The induction coil works on the principle of

The turn ratio of a transformers is given as 2 : 3. If the current through the primary coil is 3 A, thus calculate the current through load resistance(a) 1 A(b) 4.5 A(c) 2 A(d) 1. 5 A

A step up transformer has transformation ration 5 : 3. What is voltage in secondary if voltage in primary is 60 V(a) 20 V(b) 60 V(c) 100 V(d) 180 V

In a primary coil 5A current is flowing on 220 volts. In the secondary coil 2200V voltage produces. Then ratio of number of turns in secondary coil and primary coil will be(a) 1 : 10 (b) 10 : 1(c) 1 : 1    (d) 11 : 1

An ideal transformer has 500 and 5000 turn in primary and secondary windings respectively. If the primary voltage is connected to a 6V battery then the secondary voltage is(a) 0(b) 60 V(c) 0.6 V(d) 6.0 V

In a transformer, the number of turns in primary coil and secondary coil are 5 and 4 respectively. If 240 V is applied on the primary coil, then the ratio of current in primary and secondary coil is

In an inductor of inductance L = 100 mH, a current of I = 10A is flowing. The energy stored in the inductor is (a) 5 J(b) 10 J(c) 100 J  (d) 1000 J

The primary winding of transformer has 500 turns whereas its secondary has 5000 turns. The primary is connected to an ac supply of 20 V, 50 Hz. The secondary will have an output of(a) 200 V, 50 Hz(b) 2 V, 50 Hz(c) 200 V, 500 Hz(d) 2 V, 5 Hz

The number of turns in the primary coil of a transformer is 200 and the number of turns in the secondary coil is 10. If 240 volt AC is applied to the primary, the output from the secondary will be(a) 48 V(b) 24 V(c) 12 V(d) 6 V

Assertion :   Only a change in magnetic flux will maintain an induced current the coil.
Reason     : The presence of large magnetic flux through a coil maintains a current in the coil if the circuit is continuous.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

A transformer is used to(a) Change the alternating potential (b) Change the alternating current(c) To prevent the power loss in alternating current flow (d) To increase the power of current source

In a transformer the primary has 500 turns and secondary has 50 turns. 100 volts are applied to the primary coil, the voltage developed in the secondary will be(a) 1 V(b) 10 V(c) 1000 V(d) 10000 V

A step up transformer connected to a 220 V AC line is to supply 22 kV for a neon sign in secondary circuit. In primary circuit a fuse wire is connected which is to blow when the current in the secondary circuit exceeds 10 mA. The turn ratio of the transformer is(a) 50(b) 100(c) 150(d)  200

A power transformer is used to step up an alternating e.m.f. of 220 V to 11 kV to transmit 4.4 kW of power. If the primary coil has 1000 turns, what is the current rating of the secondary ? Assume 100% efficiency for the transformer(a) 4 A(b) 0.4 A(c) 0.04 A (d) 0.2 A

A step-up transformer operates on a 230 V line and supplies a load of 2 ampere. The ratio of the primary and secondary windings is 1 : 25. The current in the primary is(a) 15 A(b) 50 A(c) 25 A(d) 12.5 A

In a transformer, number of turns in the primary are 140 and that in the secondary are 280. If current in primary is 4A then that in the secondary is

In a step-up transformer the voltage in the primary is 220 V and the current is 5A. The secondary voltage is found to be 22000V. The current in the secondary (neglect losses) is

Large transformers, when used for some time, become hot and are cooled by circulating oil. The heating of transformer is due to(a) Heating effect of current alone(b) Hysteresis loss alone(c) Both the hysteresis loss and heating effect of current(d) None of the above

A transformer has 100 turns in the primary coil and carries 8 A current. If input power is one kilowatt, the number of turns required in the secondary coil to have 500V output will be(a) 100(b) 200(c) 400(d) 300

In a step-up transformer the turn ratio is 1:10. A resistance of 200 ohm connected across the secondary is drawing a current of 0.5 A. What is the primary voltage and current

In a step up transformer, 220 V is converted into 200 V. The number of turns in primary coil is 600. What is the number of turns in the secondary coil(a) 60(b) 600(c) 6000  (d) 100

A transformer has turn ratio 100/1. If secondary coil has 4 amp current then current in primary coil is(a) 4 A(b) 0.04 A(c) 0.4 A  (d) 400 A

Voltage in the secondary coil of a transformer does not depend upon.(a) Voltage in the primary coil(b) Ratio of number of turns in the two coils(c) Frequency of the source(d) Both (a) and (b)

The ratio of secondary to primary turns is 9 : 4. If power input is P, what will be the ratio of power output (neglect all losses) to power input(a) 4 : 9(b) 9 : 4(c) 5 : 4(d) 1 : 1

The number of turns in primary and secondary coils of a transformer are 100 and 20 respectively. If an alternating potential of 200 volt is applied to the primary, the induced potential in secondary will be(a) 10 V(b) 40 V(c) 1000 V(d) 20,000 V

The transformation ratio in the step-up transformer is(a) 1(b) Greater than one(c) Less than one(d) The ratio greater or less than one depends on the other factors