The resistance of a galvanometer is \(50\, ohm\) and the maximum current which can be passed through it is \(0.002\, A\). What resistance must be connected to it in order to convert it into an ammeter of range \(0 -0.5\, A\) ?....\(ohm\)

A curved in a level road has a radius \(75\, m\). The maximum speed of a car turning this curved road can be \(30 \,m / s\) without skidding. If radius of curved road is changed to \(48\, m\) and the coefficient of friction between the tyres and the road remains same, then maximum allowed speed would be .........\(m / s\).

A galvanmeter has a coil of resistance \(200 \Omega\) with a full scale deflection at \(20 \mu \mathrm{A}\). The value of resistance to be added to use it as an ammeter of range \((0-20) \mathrm{mA}\) is _______.

A current \(i\) is flowing in a straight conductor of length \(L.\) The magnetic induction at a point on its axis at a distance \(\frac {L}{4}\) from its centre will be

Unpolarized light of intensity \(I\) is incident on a system of two polarizers, \(A\) followed by \(B.\)  The intensity of emergent light is \(I/2.\)  If a third polarizer \(C\)  is placed between \(A\) and \(B,\)  the intensity of emergent light is reduced to \(I/3 .\)  The angle between the polarizers \(A\) and \(C\) is \(\theta \) . Then

A monochromatic light is incident at a certain angle on an equilateral triangular prism and suffers minimum deviation. If the refractive index of the material of the prism is \(\sqrt 3\) , then the angle of incidence....\(^o\)

A plane electromagnetic wave of frequency \(500\, MHz\) is travelling in vacuum along \(y-\)direction. At a particular point in space and time, \(\overrightarrow{ B }=8.0 \times 10^{-8} \hat{ z } \;T\). The value of electric field at this point is (speed of light \(\left.=3 \times 10^{8}\, ms ^{-1}\right)\) \(\hat{ x }, \hat{ y }, \hat{ z }\) are unit vectors along \(x , y\) and \(z\) direction.

A particular hydrogen like ion emits radiation of frequency \(2.92 \times 10^{15}\, {Hz}\) when it makes transition from \({n}=3\) to \({n}=1 .\) The frequency in \({Hz}\) of radiation emitted in transition from \({n}=2\) to \({n}=1\) will be : (in \(\,\times 10^{15}\))

Two tubes of radii \(r_1\) and \(r_2\), and lengths \(l_1\) and \(l_2\), respectively, are connected in series and a liquid flows through each of them in streamline conditions. \(P_1\) and \(P_2\) are pressure differences across the two tubes. If \(P_2\) is \(4P_1\) and \(l_2\) is \( \frac{l_1}{4}\) , then the radius \(r_2\) will be equal to

The characteristic distance at which quantum gravitational effects are significant, the Planck length, can be determined from a suitable combination of the fundamental physical constants \(G, h\) and \(c\) . Which of the following correctly gives the Planck length?

The half-life of a radioactive substance is \(T\). The time taken, for disintegrating \(\frac{7}{8}\) th part of its original mass will be