IGCSE Physics Chapters 34-48 Study Guide

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Questions and Answers

Materials such as and are attracted to magnets because they themselves become magnetized when there is a magnet nearby.

What is the difference between soft magnetic materials and hard magnetic materials?

Soft magnetic materials are easy to magnetize but lose their magnetism quickly. Hard magnetic materials are difficult to magnetize but retain their magnetism for a long time.

What are some examples of non-magnetic materials?

Examples of non-magnetic materials include brass, copper, zinc, tin, and aluminum.

What does the term 'induced magnetism' refer to?

Induced magnetism occurs when a material like iron or steel becomes magnetized when placed in a magnetic field. Signup and view all the answers

What are magnetic field lines?

Magnetic field lines are invisible lines that represent the strength and direction of a magnetic field around a magnet. Signup and view all the answers

What happens to a magnetic field between magnets with unlike poles?

When magnets with unlike poles (north and south) are placed near each other, the magnetic field lines converge, representing a stronger magnetic field, leading to attraction. Signup and view all the answers

The combined field strength between magnets with like poles is zero.

True (A) Signup and view all the answers

What is an electron and what is its role in determining the charge of an object?

An electron is a negatively charged subatomic particle. An object becomes negatively charged when it gains extra electrons and positively charged when it loses electrons. Signup and view all the answers

Explain what happens when two materials are rubbed together?

Rubbing two materials together can cause electrons to transfer from one material to the other, resulting in one material becoming negatively charged and the other becoming positively charged. Signup and view all the answers

What is earthing and why is it important?

Earthing is the process of connecting an object to the ground by a conducting material. Earthing is necessary to safely discharge unwanted charges and prevent electrical shocks. Signup and view all the answers

Define what a conductor is in the context of static electricity.

A conductor is a material that allows electrons to flow freely through it. A conductor cannot hold a charge if it is not insulated, as electrons will transfer to the ground. Signup and view all the answers

How does charging by induction work?

Charging by induction is a method of charging an object without direct contact. A charged object placed near a neutral conductor causes a redistribution of charges within the conductor, resulting in an induced charge on the conductor. Signup and view all the answers

What is the purpose of discharging a charged conductor safely?

Safe discharging of a charged conductor prevents electrical shock and potential damage by providing a conducting path for electrons to flow to the ground. Signup and view all the answers

What is the difference between charging an object by induction and charging it by direct contact?

Charging by induction involves charging an object without direct contact, using the influence of a charged object. Direct contact charging involves physical contact between the charged object and the object being charged. Signup and view all the answers

What is the S.I. unit for electric charge?

The S.I. unit for electric charge is the coulomb (C). Signup and view all the answers

Define electric current.

Electric current is the flow of electric charge through a conductor. Signup and view all the answers

What is the relationship between charge, current, and time?

Charge (Q) is the amount of electric charge flowing through a conductor, current (I) is the rate of flow of charge, and time (t) is the duration of the flow. The relationship between these three is Q = I x t, meaning charge is equal to current multiplied by time. Signup and view all the answers

Explain the difference between conventional current and electron flow.

Conventional current is depicted as flowing from the positive terminal to the negative terminal of a power source, while electron flow actually occurs from the negative terminal to the positive terminal. Signup and view all the answers

What is a series circuit and how is current affected in a series circuit?

A series circuit is a circuit with only one path for current to flow. The current remains the same at all points in the circuit. Signup and view all the answers

What is a parallel circuit and how is current affected in a parallel circuit?

A parallel circuit has multiple paths for current to flow. The current divides at each branch, creating a junction where the total current is equal to the sum of the currents in each branch. Signup and view all the answers

What is resistance?

Resistance is the opposition to the flow of electric current in a conductor. It is measured in ohms (Ω). Signup and view all the answers

What is Ohm's Law and what is its equation?

Ohm's Law states that the voltage (V) across a conductor is proportional to the current (I) flowing through it. The equation for Ohm's Law is V = I x R, where R is the resistance. Signup and view all the answers

What is the difference between an ohmic conductor and a non-ohmic conductor?

An ohmic conductor follows Ohm's Law, meaning the relationship between voltage and current is linear. A non-ohmic conductor does not follow Ohm's Law, meaning the relationship between voltage and current is non-linear. Signup and view all the answers

How can you find the equivalent resistance of resistors in a series circuit?

The equivalent resistance of a series circuit is calculated by adding up the resistances of all the individual resistors: Reffective = R1 + R2 + R3 + ... Signup and view all the answers

How can you find the equivalent resistance of resistors in a parallel circuit?

The equivalent resistance of a parallel circuit is calculated using the formula: 1/Reffective = 1/R1 + 1/R2 + 1/R3 + ... Signup and view all the answers

What is resistivity and how is it related to resistance?

Resistivity (ρ) is a material property that describes its intrinsic ability to resist the flow of electric current. Resistance (R) is directly proportional to resistivity and the length of the conductor, and inversely proportional to the cross-sectional area. Signup and view all the answers

Define electric power and provide its equation.

Electric power is the rate at which electrical energy is transferred or used. The equation for electric power is P = V x I, where V is voltage and I is current. Signup and view all the answers

How is energy transferred in an electric circuit?

Energy transferred in an electric circuit is calculated by multiplying power by the time over which energy is transferred: E = P x t, where E is energy, P is power, and t is time. Signup and view all the answers

Which of the following factors can influence the strength of an electromagnet?

All of the above (D) Signup and view all the answers

Describe the right-hand grip rule for determining the direction of the magnetic field around a current-carrying wire.

The right-hand grip rule states that if you curl your right hand around the wire with your fingers pointing in the direction of the conventional current, your thumb will point in the direction of the magnetic field. Signup and view all the answers

Explain the principle behind the operation of an electric motor.

An electric motor operates based on the interaction between a magnetic field generated by a coil carrying current and a permanent magnet. The forces created by the interaction between the magnetic fields cause the coil to rotate. Signup and view all the answers

What is electromagnetic induction?

Electromagnetic induction is the phenomenon where a changing magnetic field induces a current in a nearby conductor. Signup and view all the answers

Explain Lenz's Law in relation to electromagnetic induction.

Lenz's Law states that the direction of the induced current in a conductor is always such that it opposes the change in magnetic flux that caused the induction. Signup and view all the answers

What is Fleming's right-hand rule used for?

Fleming's right-hand rule is a mnemonic tool used to determine the direction of the induced current in a conductor moving in a magnetic field. Signup and view all the answers

What is the main function of a transformer?

A transformer is a device used to change the voltage of an alternating current. It works on the principle of electromagnetic induction and consists of two coils wound around a common magnetic core. Signup and view all the answers

What are the advantages of transmitting electricity at high voltages?

Transmitting electricity at high voltages reduces power loss due to resistance in the transmission lines, allowing for efficient and economical long-distance power delivery. It also enables using thinner, lighter, and cheaper cables. Signup and view all the answers

Explain the function of an electromagnet?

An electromagnet is a temporary magnet created by passing an electric current through a coil of wire wound around a ferromagnetic core. It produces a magnetic field when the current flows and loses its magnetism when the current is interrupted. Signup and view all the answers

What is the difference between a permanent magnet and an electromagnet?

A permanent magnet retains its magnetic properties even without an external current, while an electromagnet only produces a magnetic field when an electric current flows through its coil. Signup and view all the answers

Explain the motor effect.

The motor effect describes the phenomenon where a current-carrying conductor experiences a force when placed in a magnetic field. The direction of the force is determined by Fleming's left-hand rule. Signup and view all the answers

What is Fleming's left-hand rule and when is it used?

Fleming's left-hand rule is a mnemonic tool used to determine the direction of the force experienced by a current-carrying conductor placed in a magnetic field. It is used in situations where the magnetic field and the current are perpendicular to each other and the force acts on the conductor. Signup and view all the answers

What is the purpose of an ammeter?

An ammeter is a device used to measure the electric current flowing through a circuit. It is always connected in series with the component where the current is being measured. Signup and view all the answers

What is the difference between electromotive force (e.m.f.) and potential difference (p.d.)?

Electromotive force (e.m.f.) is the maximum potential difference (voltage) that a cell or power source can supply. Potential difference (p.d.), also known as voltage drop, is the actual voltage difference across a specific component in a circuit. The p.d. is always less than or equal to the e.m.f. Signup and view all the answers

Explain the relationship between potential difference, electrical energy, and charge.

Potential difference (V) is the energy per unit charge. Electrical energy (E) is the total energy transferred or consumed, and charge (Q) is the amount of electric charge involved. These are related by the equation: E = V x Q, meaning electrical energy is the product of potential difference and charge. Signup and view all the answers

Flashcards

Soft Magnetic Material

A material that is easily magnetized but loses its magnetism quickly. Used in electromagnets and transformers.

Hard Magnetic Material

A material that is difficult to magnetize but retains its magnetism for a long time. Used for permanent magnets.

Induced Magnetism

The process of a material becoming magnetized due to the presence of a nearby magnet.

Magnetic Field Lines

Lines that represent the direction and strength of a magnetic field. Closer lines indicate a stronger field.