Punjab Board-2019

For alloys the value of temperature coefficient of resistance is very high.

Define e..m.f. of a cell. How can you compare the emf of two cells using potentiometer ?

For metal conductors the electrical resistivity deceases with the rise in temperature

State Wheatstone bridge principle. Use Kirchhoff's Laws to obtain the relation between the resistance in four arms of the Wheatstone bridge by drawing circuit diagram.

Explain the principle, construction and working of a cyclotron with the help of a labelled diagram. State its two limitations.

A wire with an area of cross section $10 {\mathrm{mm}}^2$ has resistance $5\Omega$,when a potential difference across its ends is $25 \mathrm{V}$.calculate the drift velocity of the electron. Given the number density of electrons is $5\times {10}^{20} \mathrm{electron}/{\mathrm{m}}^3$.

A common emitter (CE) transistor has a current gain of $100$. If emitter current is $8.08 \mathrm{mA}$ma, find the base and collector current.