current electricity Questions

Alternating current cannot be measured by a D.C. ammeter because:

A $6\text{V}$ battery is connected to a network of resistors. If the equivalent resistance of the network is $1.5\Omega$, the total current supplied by the battery is:

The resistance of the series combination of two resistances is $S$. When they are joined in parallel, the total resistance is $P$. If $S=nP$, then the minimum possible value of $n$ is:

An electric current is passed through a circuit containing two wires of the same material connected in parallel. If the length and radii of the wires are in the ratio of $4/3$ and $2/3$, then the ratio of the currents passing through the wires will be:

In a metre bridge experiment, a null point is obtained at $20\text{cm}$ from one end of the wire when resistance $X$ is balanced against another resistance $Y$. If $X<Y$, then where will be the new position of the null point from the same end, if one decides to balance a resistance of $4X$ against $Y$?

Thermistors are usually made of:

Time taken by a $836\text{W}$ heater to heat one litre of water from $10^{\circ }\text{C}$ to $40^{\circ }\text{C}$ is:

The thermo emf of a thermocouple varies with the temperature $\theta$ of the hot junction as $E=a\theta +b{\theta }^2$ in volts where the ratio $a/b$ is $700^{\circ }\text{C}$. If the cold junction is kept at $0^{\circ }\text{C}$, then the neutral temperature is:

The electrochemical equivalent of a metal is $3.3\times 10^{-7}\text{kg}$ per coulomb. The mass of the metal liberated at the cathode when a $3\text{A}$ current is passed for $2\text{seconds}$ will be:

In an LCR series a.c. circuit, the voltage across each of the components, $L,C$ and $R$ is $50\text{V}$. The voltage across the $LC$ combination will be:

In a LCR circuit, capacitance is changed from $C$ to $2C$. For the resonant frequency to remain unchanged, the inductance should be changed from $L$ to: