Kerala SSLC Physics key terms

The rate at which electric charge flows through a conductor, measured in amperes. One ampere means one coulomb of charge passes a cross-section each second.

The work done in moving one unit of positive charge between two points in a circuit, measured in volts. It is the electrical 'push' that drives current through a conductor.

The property of a conductor that opposes the flow of electric current through it. It is measured in ohms and depends on length, area of cross-section, material and temperature.

At constant temperature, the current through a metallic conductor is directly proportional to the potential difference across its ends, so V divided by I stays constant.

A characteristic property of a material expressing the resistance of a conductor of unit length and unit area of cross-section. It is measured in ohm metre.

A circuit arrangement in which components are joined end to end so the same current passes through each. The total resistance equals the sum of individual resistances.

A circuit arrangement in which components are connected across the same two points, so the potential difference across each is equal while currents divide among them.

The heat produced in a resistor equals the product of the square of the current, the resistance and the time for which the current flows, written as H equals I squared R t.

The rate at which electrical energy is consumed or delivered by a device, equal to the product of potential difference and current. It is measured in watts.

A safety device containing a thin wire of low melting point that melts and breaks the circuit when current exceeds a safe value, protecting appliances from damage.

The region around a magnet or a current-carrying conductor in which its magnetic force can be detected on another magnet or on a moving charge.

Imaginary curved lines drawn to represent a magnetic field. Their direction at any point gives the field direction, and closer spacing indicates a stronger field.

A rule stating that if the right thumb points along the current in a straight conductor, the curled fingers show the direction of the magnetic field lines around it.

A long coil of insulated wire wound in the shape of a cylinder. When current flows, it behaves like a bar magnet with distinct north and south poles.

A temporary magnet made by winding a coil around a soft iron core. It is magnetic only while current flows, and its strength can be varied.

A rule giving the direction of force on a current-carrying conductor in a magnetic field: the thumb shows force, forefinger the field, and middle finger the current.

A device that converts electrical energy into mechanical energy using the force on a current-carrying coil placed in a magnetic field, made continuous by a commutator.

The production of an induced potential difference in a conductor when the magnetic flux linked with it changes, caused by relative motion or a changing current.

A current that arises in a closed coil whenever the magnetic field linked with it changes, for example when a magnet is moved towards or away from it.

A rule predicting the direction of induced current: the thumb shows the conductor's motion, forefinger the magnetic field, and middle finger the induced current.

The induced current always flows in a direction that opposes the change producing it, so the induced magnetic field acts against the motion or variation that caused it.

A machine that converts mechanical energy into electrical energy by rotating a coil in a magnetic field, producing alternating current whose direction reverses each half turn.

Two rules for mirrors: the angle of incidence equals the angle of reflection, and the incident ray, reflected ray and normal all lie in one plane.

The line drawn perpendicular to the reflecting surface at the point of incidence. All angles in reflection and refraction are measured with respect to it.

The bending of light as it passes from one transparent medium to another because its speed changes, caused by the difference in optical density of the media.

The ratio of the speed of light in vacuum to its speed in a given medium. It measures how strongly that medium bends light entering it.

An image formed when reflected or refracted rays actually meet at a point. It can be caught on a screen and is always inverted for a single lens or mirror.

An image formed when rays only appear to diverge from a point after reflection or refraction. It cannot be caught on a screen and is erect.

The splitting of white light into its component colours when it passes through a prism, because each colour is refracted through a different angle.

The band of colours produced when white light is dispersed, appearing in the order violet, indigo, blue, green, yellow, orange and red, with red deviated least.

The redirection of light in many directions by particles in a medium. Finer particles scatter shorter blue wavelengths more strongly than longer red ones.

A disturbance that transfers energy from one place to another without the medium itself moving along with the disturbance, characterised by amplitude, wavelength and frequency.

The number of complete oscillations or waves produced each second, measured in hertz. It is fixed by the source and does not change when a wave enters a new medium.

The distance between two consecutive crests or two consecutive troughs of a wave, or between two particles in the same phase of oscillation.

A sound heard again after reflection from a distant hard surface such as a wall or cliff. It is heard clearly only if the delay is at least one tenth of a second.

The product of the force applied and the displacement caused in the direction of the force. It is measured in joules and is zero when displacement is perpendicular to force.

The energy possessed by a body by virtue of its motion, equal to half the mass multiplied by the square of its speed, measured in joules.

The energy stored in a body because of its position or configuration, such as a raised object or a stretched spring, measured in joules.

The rate at which work is done or energy is transferred, equal to work divided by time. It is measured in watts, where one watt is one joule per second.

The form of energy that flows from a body at higher temperature to one at lower temperature when they are in contact, measured in joules.

A measure of the degree of hotness or coldness of a body, indicating the average kinetic energy of its particles. It decides the direction of heat flow.

The quantity of heat needed to raise the temperature of one kilogram of a substance by one kelvin, measured in joules per kilogram kelvin.

The heat absorbed or released by a substance during a change of state at constant temperature, such as melting or boiling, without any temperature change.

The smallest measurement that can be read accurately with a given instrument, found by dividing the smallest main scale division by the number of vernier divisions.

A reading shown by an instrument when the true value is zero, caused by a defect in the instrument. It must be added to or subtracted from observed readings.

An error in reading caused by viewing a scale or pointer from an angle rather than straight on, so the reading appears shifted against its true position.