A potential difference is applied across the ends of a metallic wire. If the potential difference is doubled, then the drift velocity
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$I = neA{v_d}$
$V = IR$
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The temperature coefficient of resistance for a wire is $0.00125\,^oC$. At $300\,K$ its resistance is $1\, ohm$. The temperature at which the resistance becomes $2\, ohm$ is .......... $K$
$A$ wire of cross-section area $A$, length $L_1$, resistivity $\rho_1$ and temperature coefficient of resistivity $\alpha_1$ is connected to a second wire of length $L_2$, resistivity $\rho_2$ , temperature coefficient of resistivity $\alpha_1$ and the same area $A$, so that wire carries same current. Total resistance $R$ is independent of temperature for small temperature change if (Thermal expansion effect is negligible)
A student uses the resistance of a known resistor $(1 \,\Omega)$ to calibrate a voltmeter and an ammeter using the circuits shown below. The student measures the ratio of the voltage to current to be $1 \times 10^3 \,\Omega$ in circuit $(a)$ and $0.999 \,\Omega$ in circuit $(b)$. From these measurements, the resistance (in $\Omega$ ) of the voltmeter and ammeter are found to be close to
During an experiment with a metre bridge, the galvanometer shows a null point when the joceky is pressed at $40.0 \ cm$ using a standard resistance of $90 \ \Omega$, as shown in the figure. The least count of the scale used in the meter bridge is $1 \ mm$. The unknown resistance is:
To measure the temperature coefficient of resistivity $\alpha$ of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at $25^{\circ} \mathrm{C}$ and resistance of the semiconductor arm is $3 \mathrm{~m} \Omega$. Arm BC is cooled at a constant rate of $2^{\circ} \mathrm{C} / \mathrm{s}$. If the galvanometer $\mathrm{G}$ shows no deflection after $10 \mathrm{~s}$, then $\alpha$ is :