Answer the following (MCQ): i) The larger the number of significant figures obtained in a measurement, the is the accuracy of the measurement. ii) The of the line segment drawn to scale gives the magn

$$
v_g = \frac{v_w}{n_{gw}}
$$
$$
v_g = \frac{2 \times 10^8 \text{ m/s}}{1.125}
$$
$$
v_g \approx 1.777... \times 10^8 \text{ m/s}
$$
$$
v_g \approx 1.78 \times 10^8 \text{ m/s}
$$
*   The correct option is **(d) $1.78 \times 10^8 \text{ m/s}$**.

• ix) The line joining the fictitious North Pole and South Pole of the Earth is called the Magnetic axis.

  • The correct option is (a) Magnetic axis.

• x) Radio waves are used in the study of atomic and molecular structure.

  • The correct option is (c) Radio waves.

Q.2 Answer the following (VSA):

• i) Why do random errors occur? Random errors occur due to unpredictable fluctuations in experimental conditions or measurement processes, such as slight variations in instrument readings, environmental changes, or limitations of the observer. They cannot be eliminated but can be minimized by taking multiple readings and averaging.

• ii) Define free fall. Free fall is the motion of an object solely under the influence of gravity, with no other forces like air resistance acting upon it. In free fall, all objects accelerate downwards at the same rate, regardless of their mass.

• iii) Define perfectly inelastic collision. A perfectly inelastic collision is a type of collision where the colliding objects stick together after impact and move as a single combined mass. In such a collision, kinetic energy is not conserved, but momentum is conserved.

• iv) What is gravitational force? Gravitational force is a fundamental attractive force that exists between any two objects with mass. Its magnitude depends on the masses of the objects and the distance between their centers, as described by Newton's Law of Universal Gravitation.

• v) What is a thermistor? A thermistor is a type of resistor whose resistance is highly dependent on temperature. They are typically made from semiconductor materials and are used as temperature sensors or current-limiting devices.

• vi) Optical fibres are immune to EM interference. Explain. Optical fibres transmit data using light signals, not electrical signals. Since electromagnetic interference (EMI) affects electrical signals, optical fibres are not susceptible to it. This makes them ideal for environments with high electrical noise.

• vii) What is the disadvantage of cells in parallel? A primary disadvantage of connecting cells in parallel is that if one cell has a slightly lower voltage or higher internal resistance, it can *draw current