Current Electricity

A room heater is rated 400 W, 220 V. If the supply voltage drops to 200 V, what will be the power consumed (approximately)?

Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:

[NEET 2024]

A resistor is connected to a battery of 12 V emf and internal resistance 2 Ω. If the current in the circuit is 0.6 A, the terminal voltage of the battery is:

A uniform wire of diameter d carries a current of \(100\mathrm{mA}\) when the mean drift velocity of electrons in the wire is \(v\). For a wire of diameter \(\frac{d}{2}\) of the same material to carry a current of \(200\mathrm{mA}\), the mean drift velocity of electrons in the wire is:

[Re-NEET 2024]

The material filled between the plates of a parallel plate capacitor has resistivity \(200\Omega \mathrm{m}\). The value of capacitance of the capacitor is \(2pF\). If a potential difference of \(40\mathrm{V}\) is applied across the plates of the capacitor, then the value of leakage current flowing out of the capacitor is : (given the value of relative permitivity of material is 50 )

[JEE Main 2021, 26 Aug (Shift 1)]

A charged particle having drift velocity of \( 7.5 \times 10^{-4} \mathrm{~m} \mathrm{~s}^{-1} \) in an electric field of \( 3 \times 10^{-10} \mathrm{~V} \mathrm{~m}^{-1} \), has a mobility in \( \mathrm{m}^{2} \mathrm{~V}^{-1} \mathrm{~s}^{-1} \) of:

A resistor develops 500 J of thermal energy in 20 s when a current of 1.5 A is passed through it. If the current is increased from 1.5 A to 3 A, what will be the energy developed in 20 s ?

The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is \( 0.25 \Omega \). What will be the effective resistance if they are connected in series?

[NEET 2021]

The resistance of platinum wire at \(0^{\circ} \mathrm{C}\) is \(2 \Omega\) and 6.8 \(\Omega\) at \(80^{\circ} \mathrm{C}\). The temperature coefficient of resistance of the wire is :

Due to cold weather a \(1 m\) water pipe of crosssectional area \(1 cm ^2\) is filled with ice at \(-10{ }^{\circ} C\). Resistance heating is used to melt the ice. Current of \(0.5 A\) is passed through \(4 k \Omega\) resistance. Assuming that all the heat produced is used for melting, what is the minimum time required?(Given latent heat of fusion ice \(=3.33 \times 10^5 J kg ^{-1}\), specific heat of ice \(=2 \times 10^3 J kg ^{-1}\) and density of ice \(\left.=10^3 kg / m ^3\right)\)

[JEE Main 2021, 1 Sep (Shift 2)]

10 resistors, each of resistance \(R\) are connected in series to a battery of emf \(E\) and negligible internal resistance. Then those are connected in parallel to the same battery, the current is increased \(n\) times. The value of \(n\) is :

[NEET 2023]

The solids which have the negative temperature coefficient of resistance are:

[NEET 2020]