1
JEE Main 2016 (Online) 9th April Morning Slot
+4
-1

In the circuit shown, the resistance r is a variable resistance. If for r = fR, the heat generation in r is maximum then the value of f is :
A
$${1 \over 4}$$
B
$${1 \over 2}$$
C
$${3 \over 4}$$
D
1
2
JEE Main 2016 (Offline)
+4
-1
The temperature dependence of resistance of $$Cu$$ and undoped $$Si$$ in the temperature range $$300-400$$ $$K,$$ is best described by :
A
Linear increases for $$Cu,$$ exponential decrease of $$Si.$$
B
Linear decrease for $$Cu,$$ linear decrease for $$Si$$
C
Linear increase for $$Cu,$$ linear increase for $$Si.$$
D
Linear increase for $$Cu,$$ exponential increase for $$Si$$
3
JEE Main 2015 (Offline)
+4
-1
When $$5V$$ potential difference is applied across a wire of length $$0.1$$ $$m,$$ the drift speed of electrons is $$2.5 \times {10^{ - 4}}\,\,m{s^{ - 1}}.$$ If the electron density in the wire is $$8 \times {10^{28}}\,\,{m^{ - 3}},$$ the resistivity of the material is close to :
A
$$1.6 \times {10^{ - 6}}\Omega m$$
B
$$1.6 \times {10^{ - 5}}\Omega m$$
C
$$1.6 \times {10^{ - 8}}\Omega m$$
D
$$1.6 \times {10^{ - 7}}\Omega m$$
4
JEE Main 2015 (Offline)
+4
-1

In the circuit shown, the current in the $$1\Omega$$ resistor is :
A
$$0.13$$ $$A,$$ from $$Q$$ to $$P$$
B
$$0.13$$ $$A$$, from $$P$$ to $$Q$$
C
$$1.3A$$ from $$P$$ to $$Q$$
D
$$0A$$
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