01. Ohm's Law, Resistance, Conductivity and Thermal Dependency of Resistance
Current Electricity

151876 For a wire $\frac{\mathrm{R}}{l}=\frac{1}{2}$ and length of wire $l=5 \mathrm{~cm}$. If
potential difference of $1 \mathrm{~V}$ is applied across it, current through wire will be: $(R=$ Resistance)

1 $40 \mathrm{~A}$
2 $4 \mathrm{~A}$
3 $25 \mathrm{~A}$
4 $2.5 \mathrm{~A}$
Current Electricity

151878 $n$ identical resistance are taken in which $\frac{n}{2}$ resistors are joined in series in the left gap and the remaining $\frac{n}{2}$ resistances are joined in parallel in the right gap of a metre bridge. Balancing length in $\mathrm{cm}$ is

1 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+4}$
2 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+1}$
3 $400 \cdot \frac{1}{\mathrm{n}^{2}+4}$
4 $400 \cdot \frac{1}{\mathrm{n}^{2}+1}$
Current Electricity

151879 A $100 \mathrm{~W}$ tungsten light bulb has a resistance of $250 \Omega$ when it as turned $O N$ and $25 \Omega$ when turned OFF. The ambient room temperature is $25^{\circ} \mathrm{C}$. Find the temperature of the filament when the bulb is turned $\mathrm{ON}$.
(Let, $\alpha_{\text {tungsten }}=4.5 \times 10^{-3} /{ }^{\circ} \mathrm{C}$ )

1 $2600^{\circ} \mathrm{C}$
2 $2025^{\circ} \mathrm{C}$
3 $2500{ }^{\circ} \mathrm{C}$
4 $2625{ }^{\circ} \mathrm{C}$
Current Electricity

151880 The temperature coefficient of resistance of a wire is $0.00125^{\circ} \mathrm{C}^{-1}$. At $300 \mathrm{~K}$, its resistance is $1 \Omega$. At what temperature the resistance of wire will be $2 \Omega$ ?

1 $800 \mathrm{~K}$
2 $1100 \mathrm{~K}$
3 $600 \mathrm{~K}$
4 None of the above
Current Electricity

151876 For a wire $\frac{\mathrm{R}}{l}=\frac{1}{2}$ and length of wire $l=5 \mathrm{~cm}$. If
potential difference of $1 \mathrm{~V}$ is applied across it, current through wire will be: $(R=$ Resistance)

1 $40 \mathrm{~A}$
2 $4 \mathrm{~A}$
3 $25 \mathrm{~A}$
4 $2.5 \mathrm{~A}$
Current Electricity

151878 $n$ identical resistance are taken in which $\frac{n}{2}$ resistors are joined in series in the left gap and the remaining $\frac{n}{2}$ resistances are joined in parallel in the right gap of a metre bridge. Balancing length in $\mathrm{cm}$ is

1 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+4}$
2 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+1}$
3 $400 \cdot \frac{1}{\mathrm{n}^{2}+4}$
4 $400 \cdot \frac{1}{\mathrm{n}^{2}+1}$
Current Electricity

151879 A $100 \mathrm{~W}$ tungsten light bulb has a resistance of $250 \Omega$ when it as turned $O N$ and $25 \Omega$ when turned OFF. The ambient room temperature is $25^{\circ} \mathrm{C}$. Find the temperature of the filament when the bulb is turned $\mathrm{ON}$.
(Let, $\alpha_{\text {tungsten }}=4.5 \times 10^{-3} /{ }^{\circ} \mathrm{C}$ )

1 $2600^{\circ} \mathrm{C}$
2 $2025^{\circ} \mathrm{C}$
3 $2500{ }^{\circ} \mathrm{C}$
4 $2625{ }^{\circ} \mathrm{C}$
Current Electricity

151880 The temperature coefficient of resistance of a wire is $0.00125^{\circ} \mathrm{C}^{-1}$. At $300 \mathrm{~K}$, its resistance is $1 \Omega$. At what temperature the resistance of wire will be $2 \Omega$ ?

1 $800 \mathrm{~K}$
2 $1100 \mathrm{~K}$
3 $600 \mathrm{~K}$
4 None of the above
Current Electricity

151876 For a wire $\frac{\mathrm{R}}{l}=\frac{1}{2}$ and length of wire $l=5 \mathrm{~cm}$. If
potential difference of $1 \mathrm{~V}$ is applied across it, current through wire will be: $(R=$ Resistance)

1 $40 \mathrm{~A}$
2 $4 \mathrm{~A}$
3 $25 \mathrm{~A}$
4 $2.5 \mathrm{~A}$
Current Electricity

151878 $n$ identical resistance are taken in which $\frac{n}{2}$ resistors are joined in series in the left gap and the remaining $\frac{n}{2}$ resistances are joined in parallel in the right gap of a metre bridge. Balancing length in $\mathrm{cm}$ is

1 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+4}$
2 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+1}$
3 $400 \cdot \frac{1}{\mathrm{n}^{2}+4}$
4 $400 \cdot \frac{1}{\mathrm{n}^{2}+1}$
Current Electricity

151879 A $100 \mathrm{~W}$ tungsten light bulb has a resistance of $250 \Omega$ when it as turned $O N$ and $25 \Omega$ when turned OFF. The ambient room temperature is $25^{\circ} \mathrm{C}$. Find the temperature of the filament when the bulb is turned $\mathrm{ON}$.
(Let, $\alpha_{\text {tungsten }}=4.5 \times 10^{-3} /{ }^{\circ} \mathrm{C}$ )

1 $2600^{\circ} \mathrm{C}$
2 $2025^{\circ} \mathrm{C}$
3 $2500{ }^{\circ} \mathrm{C}$
4 $2625{ }^{\circ} \mathrm{C}$
Current Electricity

151880 The temperature coefficient of resistance of a wire is $0.00125^{\circ} \mathrm{C}^{-1}$. At $300 \mathrm{~K}$, its resistance is $1 \Omega$. At what temperature the resistance of wire will be $2 \Omega$ ?

1 $800 \mathrm{~K}$
2 $1100 \mathrm{~K}$
3 $600 \mathrm{~K}$
4 None of the above
Current Electricity

151876 For a wire $\frac{\mathrm{R}}{l}=\frac{1}{2}$ and length of wire $l=5 \mathrm{~cm}$. If
potential difference of $1 \mathrm{~V}$ is applied across it, current through wire will be: $(R=$ Resistance)

1 $40 \mathrm{~A}$
2 $4 \mathrm{~A}$
3 $25 \mathrm{~A}$
4 $2.5 \mathrm{~A}$
Current Electricity

151878 $n$ identical resistance are taken in which $\frac{n}{2}$ resistors are joined in series in the left gap and the remaining $\frac{n}{2}$ resistances are joined in parallel in the right gap of a metre bridge. Balancing length in $\mathrm{cm}$ is

1 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+4}$
2 $100 \cdot \frac{\mathrm{n}^{2}}{\mathrm{n}^{2}+1}$
3 $400 \cdot \frac{1}{\mathrm{n}^{2}+4}$
4 $400 \cdot \frac{1}{\mathrm{n}^{2}+1}$
Current Electricity

151879 A $100 \mathrm{~W}$ tungsten light bulb has a resistance of $250 \Omega$ when it as turned $O N$ and $25 \Omega$ when turned OFF. The ambient room temperature is $25^{\circ} \mathrm{C}$. Find the temperature of the filament when the bulb is turned $\mathrm{ON}$.
(Let, $\alpha_{\text {tungsten }}=4.5 \times 10^{-3} /{ }^{\circ} \mathrm{C}$ )

1 $2600^{\circ} \mathrm{C}$
2 $2025^{\circ} \mathrm{C}$
3 $2500{ }^{\circ} \mathrm{C}$
4 $2625{ }^{\circ} \mathrm{C}$
Current Electricity

151880 The temperature coefficient of resistance of a wire is $0.00125^{\circ} \mathrm{C}^{-1}$. At $300 \mathrm{~K}$, its resistance is $1 \Omega$. At what temperature the resistance of wire will be $2 \Omega$ ?

1 $800 \mathrm{~K}$
2 $1100 \mathrm{~K}$
3 $600 \mathrm{~K}$
4 None of the above