Electromagnetism SAQ

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What are the two poles of a magnet called?

North-seeking pole (or north pole) and south-seeking pole (or south pole)

What is the region around a magnet where it has an effect?

A magnetic field

What does a magnetic field line indicate?

The direction a 'magnetic north' would travel in a magnetic field if free to do so

How can you plot the magnetic field due to a bar magnet?

By placing the bar magnet on a blank sheet of paper, positioning a plotting compass at one end of the magnet, and drawing dots at either end of the compass needle, then repeating this process and joining the dots. Signup and view all the answers

What is the analogy used to describe the Earth's magnetic field?

A giant bar magnet going through the centre of the Earth. Signup and view all the answers

What is the source of the magnetic field around a conductor?

The current flowing through the conductor. Signup and view all the answers

What is the purpose of the right-hand rule in relation to magnetic fields?

To determine the direction of the magnetic field around a conductor. Signup and view all the answers

How can you determine the direction of the magnetic field around a conductor using the right-hand rule?

By clasping the conductor with the right hand, with the thumb pointing in the direction of the current, and observing the direction of the fingers. Signup and view all the answers

What is the shape of the magnetic field around a long straight wire?

A series of circles around the wire Signup and view all the answers

What is the purpose of a coil of wire in an electromagnet?

To set up a magnetic field when an electric current is passed through it Signup and view all the answers

What is the direction of the magnetic flux density (B) in a magnetic field?

Along the field lines from north to south Signup and view all the answers

What is an electromagnet composed of?

A soft iron core with a coil of wire wound around it Signup and view all the answers

What happens to the magnetic field when the electric current in an electromagnet stops?

It disappears Signup and view all the answers

What is the unit of force experienced by a current-carrying conductor in a magnetic field?

Newtons (N) Signup and view all the answers

What is the formula to calculate the force on a current-carrying conductor in a magnetic field?

F = IlB Signup and view all the answers

What is the rule used to determine the direction of the force on a current-carrying conductor in a magnetic field?

Fleming's left-hand rule Signup and view all the answers

What are the three factors that affect the force on a current-carrying conductor in a magnetic field?

current, length, and magnetic field Signup and view all the answers

What is the relationship between the direction of the current, magnetic field, and force on a current-carrying conductor in a magnetic field?

perpendicular to each other Signup and view all the answers

What is the relationship between the velocity of a charged particle, the magnetic flux density, and the force experienced by the particle?

The force experienced by a charged particle is directly proportional to the velocity of the particle and the magnetic flux density, as described by the equation F = qvB. Signup and view all the answers

What is the underlying principle behind electromagnetic induction?

Electromagnetic induction is based on the principle that a change in the magnetic flux linking a circuit induces an emf. Signup and view all the answers

What are the three components that contribute to the force on a charged particle moving through a magnetic field?

The three components are the charge of the particle, its velocity, and the magnetic flux density of the field. Signup and view all the answers

What is the role of the magnetic flux density in the force experienced by a charged particle?

The magnetic flux density determines the strength of the magnetic field, which in turn affects the force experienced by the charged particle. Signup and view all the answers

What is the physical quantity that represents the total amount of magnetic field in a given region?

Magnetic flux (Φ) Signup and view all the answers

What is the formula that relates the magnetic flux, magnetic flux density, and area?

Φ = BA Signup and view all the answers

What is the relationship between the induced emf and the rate of change of flux linking a circuit, as stated by Faraday's law?

The magnitude of the induced emf is proportional to the rate of change of flux linking a circuit. Signup and view all the answers

What is the unit of magnetic flux in the SI system?

Weber (Wb) Signup and view all the answers

What is the symbol used to represent magnetic flux in equations?

Φ (phi) Signup and view all the answers

What is the purpose of a generator in relation to electromagnetic induction?

A generator converts mechanical energy into electrical energy by rotating a coil of wire within a magnetic field, causing flux to constantly change, thus inducing an EMF. Signup and view all the answers

What is the difference between an alternating current (a.c.) and a direct current (d.c.)?

An alternating current (a.c.) is an electric current whose direction reverses periodically, whereas a direct current (d.c.) is an electric current that flows continuously in the same direction. Signup and view all the answers

What is the role of Lenz's law in electromagnetic induction?

Lenz's law states that the direction of the induced emf is always such as to oppose the change causing it. Signup and view all the answers

What is the formula that relates the induced emf in a solenoid to the number of turns, magnetic flux, and time?

The formula is E = -N (dΦ/dt), where E is the induced emf, N is the number of turns in the solenoid, Φ is the magnetic flux, and t is time. Signup and view all the answers

What is the significance of the negative sign in the formula E = -N (dΦ/dt)?

The negative sign indicates that the direction of the induced emf is always opposite to the direction of the change in magnetic flux, as stated by Lenz's law. Signup and view all the answers

What is the relationship between the peak and rms values of an alternating current or voltage?

The rms value is equal to the peak value divided by the square root of 2. Signup and view all the answers

What is the formula for the rms voltage of an alternating current?

V_rms = V_0 / √2 Signup and view all the answers

What is the significance of the √2 in the formula for the rms value of an alternating current or voltage?

The √2 accounts for the oscillating nature of the alternating current or voltage, allowing the rms value to be calculated as the square root of the peak value. Signup and view all the answers

How do the peak and rms values of an alternating current or voltage relate to each other?

The rms value is proportional to the peak value, with the proportionality constant being 1/√2. Signup and view all the answers

What is the advantage of using the rms value of an alternating current or voltage instead of the peak value?

The rms value is a more useful value in many applications because it takes into account the oscillating nature of the alternating current or voltage, and is a better representation of the average value. Signup and view all the answers

What is the principle of operation of a transformer in a power station?

Mutual induction, where a changing magnetic field in one coil induces an emf in another coil. Signup and view all the answers

What is the purpose of a transformer in a power supply?

To change the voltage of a.c. power supplies. Signup and view all the answers

What is the phenomenon where a changing magnetic field in one coil induces an emf in another coil?

Mutual induction. Signup and view all the answers

What is the main application of mutual induction in electrical devices?

To change the voltage of a.c. power supplies in transformers. Signup and view all the answers

What is the role of a transformer in a power distribution system?

To step up or step down voltages. Signup and view all the answers