(a)the turns ratio (b)the current in input circuit if the output current is 2 A. Solution: (a) We know that the relation for the transformers is - Ep / Es = Np / Ns So from the above...

Solution: According to the question, Input ac voltage (Ep) is 240 V Number of turns in the primary coil (Np) is 4800 and we have to find the number of turns in secondary coil Ns =? Also, the output...

Solution: According to the question, Number of turns in primary coil (Np) is 800 and the number of turns in secondary coil (Ns) is 8 Input supply voltage Ep is 220 V Now, using the expression for...

Calculate the e.m.f. induced in the coil Solution: According to the question, decrease in the flux is = 0.005 – 0 = 0.005 weber Number of turns is 100 turns and Time is 5 seconds We know that...

(a) Ns = Np (b) Ns < Np (c) Ns > Np (d) nothing can be said Solution: In a step-up transformer Ns > Np The secondary coil of a step-up transformer has more turns than the...

(a) Fleming’s left-hand rule (b) Clock rule (c) Right hand thumb rule (d) Fleming’s right-hand rule Solution: The correct option is (d) Fleming’s left-hand rule. If we stretch out the forefinger,...

Solution: A step-up transformer reduces the current while converting low-voltage power to high-voltage electricity. High-voltage electricity is converted into low-voltage electricity by a step-down...

Solution:

Solution: The relation is as follows : Es / Ep = Ns / Np where s is for secondary and p is for primary. Explanation : A source of alternating current is applied to the primary coil in...

Solution: The size of an induced e.m.f. in a transformer's secondary coil is determined by a number of factors. (i) The ratio of the secondary coil's number of turns to the primary coil's number of...

Solution: Transformers are used to increase or decrease a.c. voltage. No, you can't utilise a transformer with a d.c. source.

Solution: AC is utilised to generate and use electricity because it has many advantages over DC. Following are some of the benefits of AC over DC: (a) A static device known as a transformer can be...

Solution: (i) The two differences between a D.C. motor and an A.C. generator are - A.C. generatorD.C....

Solution: When a generator is in use, mechanical energy is converted to electrical energy.

Solution: There are two techniques to increase the e.m.f. in an a.c. generator: (i) By increasing the coil's rotational speed. (ii) By increasing the coil's number of turns.

(a)the frequency of output voltage (b)the maximum output voltage. Solution - (a) If the speed at which the coil rotates is doubled, the frequency of an a.c. generator is also doubled. (b) The...

Solution:

An a.c. generator changes the (i) ___________ energy to (ii) ___________ energy.  Solution: (i) mechanical energy (ii) electrical energy An a.c. generator changes the mechanical energy to electrical...

Solution: The number of rotations of the coil in one second or the speed of rotation of the coil define the frequency of a.c. produced in a generator.

(a)Describe the observation in the galvanometer if  (i) the magnet is moved away rapidly, (ii) the magnet is kept stationary after it has moved into the coil, (iii) the magnet is then...

(i) In what direction does the induced current flow in the coil? (ii) Name the law used to arrive at the conclusion in part (i). (iii) How would the current in coil be altered if...

Solution: The law of conservation of energy is implied by Lenz's law. It demonstrates how the mechanical energy expended doing work, in opposition to the opposing force experienced by the rotating...

Solution: Because mechanical energy is expended in making the change....

Solution: When a coil has a large number of turns, the magnitude of induced e.m.f. increases, and the coil will oppose more according to Lenz's law. As a result, moving a magnet towards a coil...

Solution: Lenz's law is based on Faraday's law of induction, which states that when a changing magnetic field is connected to a coil, it induces an emf. Changing the magnetic field intensity by...

Solution: When a conductor coupled to a circuit travels in a magnetic field, Fleming's Right Hand Rule shows the direction of induced current.Fleming’s right-hand rule:Stretch your right hand's...

Solution: The Fleming's right hand rule can be used to calculate the direction of current induced in a conductor when it is moved in a fluctuating magnetic field.When a conductor moves in a magnetic...

(i) A current is started in a wire held near a loop of wire. (ii) The current is switched off in a wire held near a loop of wire. (iii) A magnet is moved through a loop of wire. (iv) A loop of wire...

The current is induced in a closed circuit only if there is _________ Solution: a change in a number of magnetic field lines linked with the circuit. The current is induced in a closed circuit only...

(b)State one factor that determines the magnitude of induced e.m.f. in part (a) above. (c)What factor determines the direction of induced e.m.f. in part (a) above? Solution: (a) An induced e.m.f....

(b)What is the source of energy associated with the current obtained in part (a)? Solution: (a) Magnetic flux associated with the coil changes when the coil and magnet move relative to one another....

(b)Name the phenomenon. Solution: (a) Mechanical energy is converted to electrical energy when a magnet is moved towards a coil with a galvanometer between its ends. (b) Electromagnetic induction is...

Solution: The size of the induced e.m.f. in a coil is determined by two factors: (i) On the rate of change of magnetic flux with each turn, and (ii) on the rate of change of magnetic flux with each...

Solution: The following are Faraday's two electromagnetic induction laws: (i) An e.m.f. is induced whenever the magnetic flux associated with a coil changes. Because the induced e.m.f. lasts so...

(b) Describe one experiment to demonstrate the phenomenon of electromagnetic induction. Solution: (a) Whenever the number of magnetic field lines connected to a conductor changes, an electromotive...

(a) From electrical to chemical (b) From chemical to light (c) From mechanical to electrical (d) From electrical to mechanical Solution: The correct option is (d) In an electric motor, the energy...

Solution: Electric motors are used in electrical gadgets like (a)fan, (b) washing machines, (c)refrigerators, etc.

Solution: An electric motor's rotational speed can be enhanced by: (i) increasing the current strength.(ii) Increasing the coil's number of turns.

Solution - A d.c. motor converts electrical energy into mechanical energy. Almost every mechanical action we witness in our environment is powered by an electric motor. Electric machines are a type...

Solution: A torque acts on a rectangular coil carrying electricity when it is put in a magnetic field, causing it to revolve continually. When the coil spins, the shaft connecting to it rotates as...

Solution: A device that converts electrical energy into mechanical energy is known as an electric motor. Almost every mechanical action we witness in our environment is powered by an electric motor....

(a) In which direction will the coil begin to rotate when current is passed through the coil in direction ABCD by connecting a battery at the ends A and D of the coil? (b)Why is a commutator...

(c) When will the couple acting on the coil be (i) maximum, (ii) minimum? (d) Name an instrument which makes use of the principle stated above. Solution: (c) (i) When the coil's plane is parallel to...

(a)What happens when a current is passed in the coil? (b) When will coil come to rest? Solution:...

Solution: Fleming’s left-hand rule is the law which is used to determine the direction of the force.According to this law, your left hand’s forefinger, middle finger, and thumb should all be...

Solution: Fleming’s left-hand rule is the law which is used to determine the direction of the force.According to this law, your left hand's forefinger, middle finger, and thumb should all be...

Solution: When the current in a conductor in a magnetic field is reversed, the force direction is reversed as well.Explanation : Extend the thumb, forefinger, and middle finger of the left hand...

Solution: (a) When the current in the conductor flows in the direction of the magnetic field, the force is zero. (b) When a conductor's current is perpendicular to the magnetic field, the force is...

Solution: The following are the factors that directly affect the magnitude of the force on a current-carrying conductor in a magnetic field: (i) On the magnetic field's strength B When the magnetic...

(a) Gets reversed in direction (b) Increases in strength (c) Decreases in strength (d) Remains unchanged in strength and direction Solution: The correct option is (a). On reversing the direction of...

(a) A strong magnet (b) A solenoid (c) A compass needle (d) A current-carrying wire Solution: The correct option is (c) a compass needle. The presence of a magnetic field at a point can be detected...

Solution: The 'make and break' of the circuit is critical to the operation of an electrical bell. The type of current utilized has no bearing on whether or not it works. That is, the current can...

Solution: One of the interesting properties of soft iron is that - The soft iron bar develops magnetic qualities only when an electric current travels through it. And when the current is turned off,...

Solution: ElectromagnetPermanent magnetIt is composed of soft ironIt is composed of steelIts polarity can be reversedIts polarity cannot be reversed. Also, the Electromagnets' magnetic strength can...

Solution: Electromagnets have two advantages over permanent magnets:(1) Electromagnets' magnetic strength can be increased or lowered. But the same is not possible with permanent magnets.(2)...

Solution: An electric bell uses an electromagnet. This is because the electric bell has the ability to produce magnetic field upon passing current.

Solution: The strength of an electromagnet can be enhanced in one of two ways. (i) By increasing the number of turns in the solenoid's winding and (ii) By boosting the current flowing through the...

(a) State the polarities developed at the ends A and B.  (b) How will the polarity at the ends A and B change on reversing the direction of current?(c) Suggest one-way increase the strength of...

Solution: A temporary strong magnet is created by running current via a coil coiled around a piece of soft iron. It's a man-made magnet. The strength of an electromagnet's magnetic field is...

Solution:

(b) If a piece of soft iron is placed inside the coil mentioned in part (a) and current is passed in the coil from a battery, what name is then given to the device so obtained? (c) Give one use of...

Solution - (a) At the ends, the polarity is as follows: X is for south pole.Y is for north pole.(b) Increasing the current flow in the coil is one technique to improve the electromagnet's...

Solution:

(a) When current flows in a wire, it creates ____________ (b) On reserving the direction of current in a wire, the magnetic field produced by it gets _____. (C)A current carrying solenoid behaves...

Solution: When a soft iron bar is placed within the solenoid, the magnetic field increases. Explanation : The soft iron core aids in concentrating magnetic lines of force through the solenoid,...

Solution: Due to the solenoid at that point, the compass needle will rest in the direction of the magnetic field. Explanation : The Right hand thumb rule can readily determine the polarity of the...

Solution: At rest, a current-carrying freely suspended solenoid behaves similarly to a bar magnet. As a result, when a current-carrying solenoid is suspended freely. It sets itself in the same...

Solution: The magnetic field produced by a current-carrying solenoid can be amplified in several ways. (i) By increasing the number of turns in the solenoid's winding and(ii) By boosting the current...

(a) What will be the polarity at the ends A and B? (b) How will the compass needle be affected? Give reason. (a) The north pole is at the end of A, and the south pole is at the end of B.(b) The...

(a) State the polarity at the ends A and B. (b) Will the magnet be attracted or repelled? Give a reason for your answer. Solution: (a) The north pole is at the end A, and the south pole is at the...

Solution: The right hand thumb rule is the name of the rule. It asserts that if the current-carrying conductor is held in the right hand with the thumb pointing in the direction of current flow, the...

Solution:

(i) the clockwise, (ii) the anticlockwise, direction? Solution: (i) The magnetic field in a clockwise direction is directed inwards along the coil's axis.(ii) The magnetic field in an anticlockwise...

Solution: When a wire bent into a circle carries a current in an anticlockwise direction, the face of the coil exhibit north polarity.

Solution:

Solution: The compass needle is deflected when a current is passed through a conductor wire. This creates a magnetic field surrounding it. As a result, the compass needle will deflect.

(a) What will be the direction of the magnetic field at a point just underneath it? (b) Name the law used to arrive at this answer in part (a). Solution: (a) At a position immediately beneath the...

Solution: The right-hand thumb rule determines the direction of the magnetic field surrounding a current-carrying wire. It claims that if we hold the current-carrying conductor in our right hand...

(a) decreased, (b) reversed? Solution: (a) As the current is reduced, the magnetic field lines grow fewer. (b) When the direction of current is reversed, the magnetic field is reversed as...

Solution:

Solution: Experiment: A wire AB, running north-south, is linked to a battery through a rheostat and a tapping key in Figure. A compass needle is set just below the wire.Observations:(1) When the key...