Physics Test - ...

In the system shown in figure block is pulled by applying a force of 40 N on the other end of string. If the kinetic energy of the block increases by 40 J in a given interval of time then work done by tension on the block is (g=10 m/s²)

An electric dipole is placed at the origin and is directed along the \(x\) -axis. At a point \(P\), far away from the dipole, the electric field is parallel to the \(y\) -axis. OP makes an angle \(\theta\) with the \(x\) -axis, then -

How long will a radioactive isotope, whose half life is Tyears, take for its activity to reduce to 1/8th of its initial value?

Two conducting spheres \(A\) and \(B\) of radius \(a\) and \(b\) respectively are at the same electric potential. The ratio of the surface charge densities of \(\mathrm{A}\) and \(\mathrm{B}\) is

A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

The primary winding of a transformer has 100 turns and its secondary winding has 200 turns. The primary winding is connected to an AC supply of \(120 \mathrm{V}\) and the current flowing in it is \(10 \mathrm{A}\). The voltage and the current in the secondary winding is

A telephone wire of length $200\text{km}$ has a capacitance of $0.014\mu \mathrm{F}$ per km.If it carries an AC frequency $5\text{kHz,}$ what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum?

Uranium-238 decays to thorium-234 with half-life $5\times {10}^9\mathrm{ }\mathrm{y}\mathrm{r}$ . The resulting nucleus is in the excited state and hence further emits $\mathrm{\gamma }$ -rays to come to the ground state. It emits $\mathrm{20 }\mathrm{\gamma }$ -rays per second. The emission rate will drop to $\mathrm{5 }\mathrm{\gamma }$ rays per second in

A large parallel plate capacitor, whose plates have an area of \(1 \mathrm{m}^{2}\) and are separated from each other by \(1 \mathrm{mm}\), is being charged at a rate of \(25 \mathrm{V} \mathrm{s}^{-1}\). If the dielectric between the plates has the dielectric constant 10 , then the displacement current at this instant is

When the frequency of the AC voltage applied to a series LCR circuit is gradually increased from a low value, the impedance of the circuit