A silver wire has a resistance of 2.1 Ω at 27.5 °C, and a resistance of 2.7 Ω at 100 °C. Determine the temperature coefficient of resistivity of silver.
Temperature, \(T_1 = 27.5 °C\)
Resistance of the silver wire at \( T_1, R_1 = 2.1 Ω \)
Temperature, \(T_2 = 100°C\)
Resistance of the silver wire at \(T_2, R_2 = 2.7 Ω\)
Temperature coefficient of silver = α
It is related with temperature and resistance as
\(α = \frac{R_2-R_1}{R_1(T_2-T_1)}\)
\(α = \frac{2.7-2.1}{2.1(100-27.5)}\)
\(α = 0.0039 °C^{-1}\)
Therefore, the temperature coefficient of silver is \(0.0039 °C^{−1}.\)

The equivalent resistance between the points \(A\) and \(B\) in the given circuit is \[ \frac{x}{5}\,\Omega. \] Find the value of \(x\). 
A Wheatstone bridge is initially at room temperature and all arms of the bridge have same value of resistances \[ (R_1=R_2=R_3=R_4). \] When \(R_3\) resistance is heated, its resistance value increases by \(10%\). The potential difference \((V_a-V_b)\) after \(R_3\) is heated is _______ V. 

A ladder of fixed length \( h \) is to be placed along the wall such that it is free to move along the height of the wall.
Based upon the above information, answer the following questions:
(iii) (b) If the foot of the ladder, whose length is 5 m, is being pulled towards the wall such that the rate of decrease of distance \( y \) is \( 2 \, \text{m/s} \), then at what rate is the height on the wall \( x \) increasing when the foot of the ladder is 3 m away from the wall?