Class 10 : Practice Questions and Answers

The pupil regulates the amount of light entering the eye by adjusting its size. It becomes smaller in bright light and larger in dim light for optimal vision.

An electromagnet produces a temporary magnetic field when electric current flows through it. The field can be switched on or off by controlling the current.

A concave mirror is used in car headlights to focus and direct light in a specific direction, enhancing visibility.

The retina detects light and converts it into electrical signals, which are sent to the brain for interpretation, allowing us to see.

The near point is the closest distance at which the eye can clearly focus. For a normal person, this is approximately 25 cm.

Electrical power is the rate at which energy is consumed or generated. It is calculated as Power = Current × Voltage, measured in watts.

Magnetic field strength is measured in tesla (T), named after Nikola Tesla. One tesla represents a field of 1 newton per ampere-metre.

When electric current flows through a conductor, the magnetic field forms concentric circular loops around the wire. The direction can be determined using the right-hand thumb rule.

A resistor reduces the flow of electric current in a circuit by providing resistance, helping control the amount of current passing through other components.

A rainbow is caused by the dispersion of sunlight in water droplets. Different wavelengths refract at different angles, separating white light into its component colors.

The lens of the eye focuses light onto the retina by changing shape to accommodate objects at different distances, aiding clear vision.

When light enters a rarer medium from a denser medium, it bends away from the normal due to refraction, changing its speed and direction.

The critical angle is the angle of incidence at which light passing from a denser to a rarer medium undergoes total internal reflection. Beyond this angle, no refraction occurs.

Newton's law of inertia states that an object will remain at rest or continue moving at constant velocity unless acted upon by an external force.

Work = Force × Distance, where force is in newtons and distance is in metres.

The SI unit of work is the joule (J). It is the energy transferred when a force of one newton acts over a distance of one metre.

The Sun is the primary source of energy on Earth, providing light and heat that sustain life, drive weather patterns, and enable photosynthesis.

Gravitational force is a non-contact force that acts at a distance, pulling objects towards the centre of the Earth or other celestial bodies without physical contact.

A battery stores chemical energy. When connected to a circuit, this chemical energy is converted into electrical energy to power devices.

Frequency is measured in hertz (Hz), representing the number of cycles or oscillations per second. One hertz equals one cycle per second.