Electromagnetic Induction

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Electromagnetic Induction If  a wire is moved through a magnetic field in such a way that it cuts the  magnetic lines of force, a voltage ... Read More

Moving coil loud speaker (physics)

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Moving coil loud speaker When the varying current is supplied into the coil, the coil is magnetized and vibrates backwards and forwards, with the same ... Read More

Mode of action  telephone receiver (physics)

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Mode of action  telephone receiver (physics) The varying current from the microphone passes through the coil of electromagnets, soft iron gets magnetized and pull the ... Read More

Electric bell

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Electric bell When the switch is closed, current flows through the circuit and the core become magnetized The iron armature is attracted towards the magnetized ... Read More

Magnetic field pattern due to solenoid

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Magnetic field pattern due to solenoid Please Subscribe to promote this website. Subscription is free Share with a friend Your comments are highly welcome Thank ... Read More

Magnetic field pattern due to parallel conductors

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Magnetic field pattern due to parallel conductors   Please Subscribe to promote this website. Subscription is free Share with a friend Your comment is valuable ... Read More

Magnetic field pattern due to a coil

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Magnetic field pattern due to a coil Please Subscribe to promote this website. Subscription is free Share with a friend Your comment is valuable Your ... Read More

Magnetic field on straight conductor carrying current into or out of the paper

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Magnetic field pattern on straight conductor carrying current into or out of the paper Please Subscribe to promote this website. Subscription is free Share with ... Read More

Magnetic flux pattern due to soft iron in earth’s horizontal magnetic field

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Magnetic flux pattern due to soft iron in earth’s horizontal magnetic field Please Subscribe to promote this website. Subscription is free Share with a friend ... Read More

Magnetic flux pattern of a horizontal bar magnet in earth’s magnetic field

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Magnetic flux pattern of a horizontal bar magnet in earth’s magnetic field South Pole, S, of bar magnet facing to north (attraction occurs) North Pole, ... Read More

Experiment to determine magnetic meridian

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Experiment to determine magnetic meridian A permanent bar magnet is suspended on a retort stand using a thread and allowed to settle. The vertical plane ... Read More

An experiment to determine the magnetic field pattern of bar magnet using iron fillings.

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An experiment to determine the magnetic field pattern of bar magnet using iron fillings. A cardboard is placed on a magnet and iron fillings sprinkled ... Read More

Soft  and hard magnetic substances

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Soft  and hard magnetic substances Soft magnetic materials are substance that are easily magnetized and easily lose magnetism, e.g. soft iron. Soft magnetic materials are ... Read More

Storing magnets

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Storing magnets Small pieces of soft iron called keepers are placed across opposite poles of two bar magnets These iron keepers become induced magnets and ... Read More

Methods of demagnetization

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Demagnetization Demagnetization is the process through which magnets lose their magnetism Demagnetization result in scattering molecular magnets to face in randomly.   Methods of demagnetization ... Read More

Magnetic saturation

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Magnetic saturation This is the maximum level of magnetization when the resultant magnetic axes of all domains in magnetic material are aligned with the magnetizing ... Read More

Magnetization or methods of making a magnet

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Magnetization This is a process by which randomly arranged molecular magnet of a ferromagnetic material are arranged to point in one direction.  Methods of magnetization ... Read More

Magnetic domain theory

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Magnetic domain theory A magnet is made us of tiny molecular magnets called dipole arranged in groups called magnetic domains, lined up with their N-poles ... Read More

How to test for polarity of am magnet

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Testing for polarity of a pole A known pole of magnet is brought near the ends of a material suspected to be a magnet. If ... Read More

Laws of magnetism

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Laws of magnetism Like poles of magnets repel; g. when a north pole is brought near a north pole or a south pole brought near ... Read More

What are uses of magnets

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Uses of magnets In construction of cycle dynamos, telephones, loud speaker, electric meters, current measuring instruments. To remove metal splinters from oil engine For door ... Read More

What is magnetism?

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Magnetism is the ability of substances to attract and/or repel others Please Subscribe to promote this website. Subscription is free Share with a friend Your ... Read More

(ii) Sketch graphs to show the time-dependence of supplied voltage and the current in the circuit.

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Sketch graphs to show the time-dependence of supplied voltage and the current in the circuit. Please Subscribe to promote this website. Subscription is free Share ... Read More

Discuss the factors which determine the maximum e.m.f generated by a dynamo.

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Discuss the factors which determine the maximum e.m.f generated by a dynamo. Induced e.m.f, E = 2πfNBAsin 2πft Maximum e.m.f, E0 = 2πfNBA Thus maximum ... Read More

Give two practical applications of this Eddy currents

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Give two practical applications of this Eddy currents damping of moving coil meters melting metals in induction furnaces breaking in electric train   Please Subscribe ... Read More

Explain the term back e.m.f in a d.c motor.

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Explain the term back e.m.f in a d.c motor. As the motor rotates the magnetic field, the flux linking changes. This induces an e.mf in ... Read More

Explain the advantages of a.c over d.c in power transmissions

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Explain the advantages of a.c over d.c in power transmissions c can easily be stepped up and down c is easy to generate c can ... Read More

Describe an experiment to demonstrate mutual induction

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Describe an experiment to demonstrate mutual induction Coil A and B are placed close to each other. When K is closed bulb P lights. Hence ... Read More

Describe how you would determine the value of the earth’s magnetic flux density at a place, using a search coil.

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A coil of known number of turns, N (about 100) and area A is connected to a calibrated ballistic galvanometer so that the total resistance ... Read More

What is hysteresis loss ? 

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What is hysteresis loss ?  Hysteresis loss is the loss in energy due to the magnetic domains from one direction to the other as current ... Read More

Describe with aid of a labelled diagram the structure and action of a hot wire ammeter.

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Describe with aid of a labelled diagram the structure and action of a hot wire ammeter. The current flows through a fine resistance-wire XY, which ... Read More

What is meant by the terms reactance and impedance as applied to alternating currents. 

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What is meant by the terms reactance and impedance as applied to alternating currents.  Reactance is non resistive opposition to the flow of a.c in ... Read More

Describe with the aid of a diagram, an absolute method of measuring current.

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Describe with the aid of a diagram, an absolute method of measuring current. Current balance is based on principles of moments The apparatus setup is ... Read More

Describe the structure and mode of operation of the repulsion type moving iron meter.

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Describe the structure and mode of operation of the repulsion type moving iron meter. When a current is passed through the coil, the iron rods ... Read More

Explain why a capacitor in a circuit blocks the flow of direct current but allows the flow of alternating current

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Explain why a capacitor in a circuit blocks the flow of direct current but allows the flow of alternating current. When a capacitor is connected ... Read More

(iii) Sketch using the same axes the graphs of charge Q on the capacitor and current I in the circuit against time.

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Sketch using the same axes the graphs of charge Q on the capacitor and current I in the circuit against time. Explanation of the curve ... Read More

What is a sinusoidal alternating current?

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What is a sinusoidal alternating current? A sinusoidal a.c is aperiodic current whose time dependence is given by sine function.   Please Subscribe to promote ... Read More

Describe with aid of a diagram, an experiment to verify Faraday’s law of electromagnetic induction

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Describe with aid of a diagram, an experiment to verify Faraday’s law of electromagnetic induction X and Y are brush contact. A copper rod which ... Read More

Describe an experiment to measure the magnetic flux density between the pole pieces of a strong magnet.

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Describe an experiment to measure the magnetic flux density between the pole pieces of a strong magnet. A search coil is connected to a ballistic ... Read More

Define the ampere

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Define the ampere The ampere is steady current flowing in negligible cross-section, one meter apart in vacuum when the force between them is 2 x ... Read More

(iii) Explain why the current in the primary coil of a transformer increases when the secondary is connected to the load.

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Explain why the current in the primary coil of a transformer increases when the secondary is connected to the load. When load is connected to ... Read More

Describe the structure and mode of action of the deflected magnetometer

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Describe the structure and mode of action of the deflected magnetometer It consists of a small compass needle (small magnet) which is pivoted on a ... Read More

Magnetic variance

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Magnetic variance Magnetic variation is the angle between the magnetic and geographical meridians. Or, angle between the earth’s magnetic axis and geographical axis. Please Subscribe ... Read More

Magnetic meridian 

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Magnetic meridian  Magnetic meridian is a vertical plane in which a freely suspended magnet sets itself. Please Subscribe to promote this website. Subscription is free ... Read More

Magnetic meridian

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Magnetic meridian. Magnetic meridian is a vertical plane in which a freely suspended magnet sets itself.   Please Subscribe to promote this website. Subscription is ... Read More

How can a d.c. generator be converted into an a.c. generator.

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How can a d.c. generator be converted into an a.c. generator. To convert a d.c. generator to an a.c. generator, the ends of the rectangular ... Read More

How can a d.c. generator be converted into an a.c. generator.

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How can a d.c. generator be converted into an a.c. generator. To convert a d.c. generator to an a.c. generator, the ends of the rectangular ... Read More

Describe briefly the factors that determine the peak value of the induced e.m.f in d.c generator

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Describe briefly the factors that determine the peak value of the induced e.m.f in d.c generator The peak value of induced e.m.f increases with increase ... Read More

(ii) Describe with the aid of a labelled diagram the structure and mode of operation of a d.c generator.

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Describe with the aid of a labelled diagram the structure and mode of operation of a d.c generator. B1 and B2 are carbon brushes, C1 ... Read More

what is the difference between a motor and a dynamo? 

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What is the difference between a motor and a dynamo?  A dynamo converts mechanical energy to electrical energy while a motor converts electrical energy into ... Read More

Describe how a thermocouple ammeter is used to measure an alternating current

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Describe how a thermocouple ammeter is used to measure an alternating current P and Q are dissimilar wires Current to be measured is passed through ... Read More

Sketch using the same axes the variation of applied voltage and current through the inductor with time

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Sketch using the same axes the variation of applied voltage and current through the inductor with time   Please Subscribe to promote this website. Subscription ... Read More

Explain the structural modification needed to convert an a.c. generator into a d.c. generator.

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Explain the structural modification needed to convert an a.c. generator into a d.c. generator. The slip rings are replaced by commutators and the brushes are ... Read More

Write down and expression for the e.m.f generated by a dynamo and use it to identify the factors which determine the maximum e.m.f.

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Write down and expression for the e.m.f generated by a dynamo and use it to identify the factors which determine the maximum e.m.f. Induced e.m.f ... Read More

Describe the feature of earth’s magnetic field

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Describe the feature of earth’s magnetic field Geographical meridian is the vertical plane containing the geographical axis Magnetic meridian is the vertical plane containing magnetic ... Read More

Describe an experiment to determine the magnetic flux density of a uniform magnetic field using a search coil and ballistic galvanometer

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Describe an experiment to determine the magnetic flux density of a uniform magnetic field using a search coil and ballistic galvanometer A search coil of ... Read More

Define magnetic flux density. 

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Define magnetic flux density.  Magnetic flux is the force acting on conductor of length 1m and carrying of 1A placed perpendicular to magnetic field. Please ... Read More

Explain the steps taken to minimize power losses in electric power transformation.

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Explain the steps taken to minimize power losses in electric power transformation.  - Voltage generated is stepped up using a transformer so as to transmit ... Read More