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From Hooke's law, F = kx where x = extension, k = force constant K = 680Nm\(^{-1}\), F = 306N x = \(\frac{\text{F}}{\text{x}}\) = \(\frac{306}{680}\) ≈ 0.450m Fractional Change in Length: Given the fractional change is 1.5: 1.5 = \(\frac{\text{x}}{\text{L}}\) L = \(\frac{0.450}{1.5}\) = 0.30m.

Vacuum: It prevents conduction and convection because there are no air molecules to transfer heat. Silvered Walls: They minimize radiation by reflecting thermal radiation back.

Thermal expansion can affect accuracy and timekeeping in a watch's balance wheel, making it disadvantageous in this application.

The given graph illustrates the anomalous expansion of water, where water has its highest density and consequently its lowest volume at 4ºC

Heat gained by 25º C body = Heat lost by 35º C body M\(_c\) c \(\delta\)\(\theta\) = M\(_h\) c\(\delta\)\(\theta\) 70 x c x (f - 25) = 70 x c x (35 - f) where f = final temperature f - 25 = 35 - f (f and 70 cancel out) 2f = 35 + 25 = 60 f = \(\frac{60}{2}\) = 30ºC

specific heat capacity of water = 4200Jkg\(^{-1}\)k\(^{-1}\), Specific heat of vaporization of water = 2.26 x 10\(^6\)Jkg\(^{-1}\), mass of water = 0.02kg, water vapour temp. = 100ºC, water at 97ºC The amount of heat required = ML + Mc\Delta\(\theta\) = 0.02 x 2.26 x 10\(^6\) + 0.02 x 4200 x (100 - 97) = 45,200 + 252 = 45,452J.

The constant temperature at which a liquid changes into gaseous state is known as its boiling point.

Voltage across shunt = Voltage across galvanometer I\(_s\)R\(_s\) = I\(_g\)R\(_g\) R\(_g\) = 5\(\Omega\), I\(_g\) = 10mA = 0.01A, I\(_s\) = 2 - 0.01 = 1.99A R\(_s\) = \(\frac{I_g \times R_g}{I_s}\) = \(\frac{0 .01 \times 5}{1.99}\) = 0.025\(\Omega\)

Keepers reduce self-demagnetization of magnets by providing a low reluctance path for magnetic flux, thereby containing the flux within the keeper.

When electricity is transmitted over long distances, power losses occur mainly due to the resistance of the transmission lines. These losses are proportional to the square of the current (I\(^2\)R losses). By using high voltage, the current can be kept low, significantly reducing these losses

F = \(\frac{Kq_1q_2}{r^2}\) F = \(\frac{9 \times 10^9 \times (1.0 \times 10^{-6})^2}{(0.2)^2}\) = 2.25 x 10\(^{-1}\)N

If lamp S goes off, all other lamps will go off. This is because lamp S is required to complete the whole circuit.

A mica capacitor has mica as its dielectric material. Known for excellent stability, low loss, and high insulation resistance, they are used in precision applications, particularly in RF circuits and high-frequency settings.

When a dielectric is placed between the plates, it increases the capacitance by reducing the electric field and allowing more charge to be stored.

When the current flowing through the fuse exceeds its rated value, the fuse element melts, breaking the circuit and preventing further flow of electricity. This helps prevent overheating and potential fires.