Dependence of Resistance on Temperature

Q. A nichrome element has a resistance of $75.3\Omega$ at ${27}^{\circ }C$. When 230 V p.d is applied and a study state temperature is reached, the current flowing through it is 2.68 A. If $\propto =1.7\times {10}^{-4\circ }{C}^{-1}$, find the steady state temperature

1. ${1000}^{\circ }C$
2. ${700}^{\circ }C$
3. ${950}^{\circ }C$
4. ${848}^{\circ }C$

Q. The voltage V and current I graph for a conductor at two different temperatures $T_1$ and $T_2$ are shown in the figure. The relation between $T_1$ and $T_2$ is

1. $T_1>T_2$
2. $T_1\approx T_2$
3. $T_1=T_2$
4. $T_1<T_2$

Q. A resistance coil of 60ohms is immersed in 42kg of water. A current of 7A is passed through it. The rise in temperature of water per minute is

Q. The current voltage (I – V) graphs for a given metallic wire at two different temperatures $T_1$ and $T_2$ are shown in figure. If follows from the graphs that

1. $T_1>T_2$
2. $T_1<T_2$
3. $T_1=T_2$
4. $T_1$ is greater or less than $T_2$ depending on whether the resistance R of the wire is greater or less than the ratio $V/I$

Q. The temperature coefficient of resistance of a conductor varies as $\alpha \left(T\right)=3T^2+2T$. If $R_0$ is resistance at $T=0$ and $R$ be resistance at $T$ then

1. $R=R_0(6T+2)$
2. $R=2R_0(3+2T)$
3. $R=R_0(1+T^2+T^3)$
4. $R=R_0(1-T+T^2+T^3)$

Q. Two resistors have resistances $R_{01}$ and $R_{02}$ at $0^{\circ }C$ and temperature co -efficient $\propto 1$ and $\propto 2$. Find the value of $\propto$ for their series combination.

1. ${\propto }_1+{\propto }_2$
2. ${\propto }_1-{\propto }_2$
3. $\frac{R_{01}{\propto }_1+R_{02}{\propto }_2}{R_{01}+R_{02}}$
4. $\frac{R_{01}{\propto }_2+R_{02}{\propto }_1}{R_{01}+R_{02}}$

Q. A conductor at ${10}^{\circ }$C connected in the left gap of metre bridge gives balancing length 40 cm. When the conductor is at ${60}^{\circ }$C, the balance point shifts by 5cm. The temperature coefficient of resistance of the material of the conductor is

1. $\frac{1}{{210}^{\circ }C}$
2. $\frac{1}{{220}^{\circ }C}$
3. $\frac{1}{{200}^{\circ }C}$
4. $\frac{1}{{201}^{\circ }C}$

Q.

Temperature coefficient of resistance of platinum is $4\times {10}^{-3}{K}^{-1}$ at $0^{\circ }$C. The temperature at which the increase in the resistance of platinum wire is 10% of its value at $0^{\circ }$C.

1. ${250}^{\circ }C$
2. ${500}^{\circ }C$
3. ${50}^{\circ }C$
4. ${25}^{\circ }C$

Q. The resistance of wire at ${20}^{\circ }C$ is $20\Omega$, and at ${300}^{\circ }C$ resistance of wire is $50\Omega$. The temperature at which its resistance will be $40\Omega$ is

1. ${100}^{\circ }C$
2. ${107}^{\circ }C$
3. ${207}^{\circ }C$
4. ${200}^{\circ }C$

Q. The temperature co-efficient of resistance of a wire is $0.00125{/}^{\circ }C$. At 300 K , it’s resistance is $1\Omega$. The resistance of the wire will be $2\Omega$ at

1. 1154 K
2. 1127 K
3. 600 K
4. 1400 K