The volume of a block of metal at $30^{\circ} \mathrm{C}$ changes by $0.12 \%$ when its temperature is increased to $70^{\circ} \mathrm{C}$. The coefficient of linear expansion of the metal is
A galvanometer of resistance ' $G$ ' can be converted into a voltmeter of range ( $0-\mathrm{V}$ ) volt by connecting a resistance ' $R$ ' in series with it. The resistance ' $R$ required to change its range from $\left(0-\frac{\mathrm{V}}{4}\right)$ volt will be
A light metal disc of radius ' $r$ ' floats on water surface and bends the surface downwards along the perimeter making an angle ' $\theta$ ' with the vertical edge of the disc. If the weight of water displaced by the disc is ' W ', the weight of the metal disc is [ $\mathrm{T}=$ surface tension of water]
The magnetic field at the centre of a current carrying circular coil of area ' $A$ ' is ' $B$ '. The magnetic moment of the coil is ( $\mu_0=$. permeability of free space)