1
JEE Main 2016 (Online) 9th April Morning Slot
+4
-1
A 50 $$\Omega$$ resistance is connected to a battery of 5 V. A galvanometer of resistance 100 $$\Omega$$ is to be used as an ammeter to measure current through the resistance, for this a resistance rs is connected to the galvanometer. Which of the following connections should be employed if the measured current is within 1% of thecurrent without the ammeter in the circuit ?
A
rs = 0.5 $$\Omega$$ in parallel with the galvanometer
B
rs = 0.5 $$\Omega$$ in series with the galvanometer
C
rs = 1 $$\Omega$$ in series with galvanometer
D
rs =1 $$\Omega$$ in parallel with galvanometer
2
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
3
JEE Main 2016 (Offline)
+4
-1
A galvanometer having a coil resistance of $$100\,\Omega$$ gives a full scale deflection, when a currect of $$1$$ $$mA$$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $$10$$ $$A,$$ is :
A
$$0.1\,\Omega$$
B
$$3\,\Omega$$
C
$$0.01\,\Omega$$
D
$$2\,\Omega$$
4
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
$$1.6 \times {10^{ - 7}}\Omega m$$
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