Current electricity practice · Mixed difficulty

The equivalent resistance of resistor connected in series is always

As the temperature rises the resistance offered by metal

What determines the emf between the two metals placed in an electrolyte?

When a current passes through the junction of two different metals, evolution or absorption of heat at the junction is known as

The drift velocity of the electrons in a current carrying conductor is of the order of:

Resistance of conductor is doubled keeping the potential difference across it constant. The rate of generation of heat will

The resistance of a $240 \mathrm{~V}$ and $200 \mathrm{~W}$ electric bulb when hot is 10 times the resistance when cold. Find its resistance at room temperature. If the working temperature of the filament is $2000^{\circ} \mathrm{C}$, find the temperature coefficient of the filament.

A $100\,\,watt$ bulb working on $200\,\,volt$ and a $200\,\,watt$ bulb working on $100\,\,volt$ have

An ammeter with internal resistance $90\,\,\mathrm{\Omega }$ reads $1.85\,\,A$ when connected in a circuit containing a battery and two resistors $700\,\,\mathrm{\Omega }$ and $410\,\,\mathrm{\Omega }$ in series. Actual current will be

A thermocouple is formed by two metals $X$ and $Y$, metal $X$ comes earlier to $Y$ in Seebeck series. If temperature of hot junction increases beyond the temperature of inversion, then direction of current in thermocouple will be from

Five hundred cells of same emf $E$ and same internal resistance $r$ are connected in series to form a loop in same order (without external resistance). The potential drop across 199 cells is found to be

The tolerance level of a resistor with the colour code red, blue, orange, gold is

Which of the following relation is wrong?

Fifty electric bulbs, all identical, are connected in series across the mains of a $\mathrm{220}\,\,\mathrm{V}$ supply. After one bulb is fused, the remaining $\mathrm{49}$ bulbs connected in series across the same mains. The illumination will be

A potential difference ${V}$ is applied to a copper wire of diameter $d$ and length $L$. There will be no effect on the electron drift speed after doubling which of the parameter

Two identical cells send the same current in $3\,\,\Omega$resistance, whether connected in series or in parallel. The internal resistance on the cell should be

Two electric bulbs, one of $200\,\,volt\,\,40\,\,watt$ and the other $200\,\,volt\,\,100\,\,watt$ are connected in a house wiring circuit

The resistance of a metal increases with increasing temperature because

Emf of lead accumulator after complete charging is

By using only two resistances coils-singly, in series or in parallel one should be able to obtain resistance of $\mathrm{3,4,12 }\,\mathrm{and }\,\mathrm{16 }\,\mathrm{ohm}$. The separate resistance of the coil are

If $n$ cells each of emf $\varepsilon$ and internal resistance $r$ are connected in parallel, then the total emf and internal resistances will be

There are two electric bulbs of $40\,\,W$ and $100\,\,W$. Which one will be brighter when first connected in series and then in parallel

Pick out the wrong statement

The electrical conductivity of earth's atmosphere

Two bulbs rated $\left( {25\,\,w - 220\,\,v} \right)$ and $\left( {100\,\,w - 220\,\,v} \right)$ are connected in series to $440\,\,v$ time. Which one likely to fuse?

A battery is charged to a voltage of $15 \mathrm{~V}$ for 8 hours with $10 \mathrm{~A}$ current. On discharge, the battery supplies a current of $5 \mathrm{~A}$ for 15 hours at a mean terminal voltage of $14 \mathrm{~V}$. The efficiency of the battery is

Ohm's law is valid if

It takes 12 minutes to boil 1 litre of water in an electric kettle. Due to some defect it becomes necessary to remove $20 \%$ turns of heating coil of the kettle. After repair, how much time will it take to boil 1 litre of water?

The current in a conductor varies with time $t$ as $I = 2t + \,\,3{t^2}$ where $I$ is in ampere and $t$ in seconds. Electric charge flowing through a section of the conductor during $t = 2\,\,\sec$ to $t = 3\,\,\sec$ is

A potentiometer wire of length $1\,\,m$ and resistance $10\,\,\mathrm{\Omega }$ is connected in series with a cell of $emf\,\,2\,\,V$ with internal resistance $1\,\,\mathrm{\Omega }$ and a resistance box including a resistance $R.$. If potential difference between the ends of the wire is $1\,\,mV$, the value of $R.$ is