Potentiometer wire of length 1 m is connected in series with 490 Ω resistance and 2 V battery. If 0.2 mV / cm is the potential gradient, then resistance of the potentiometer wire is

Question

Potentiometer wire of length 1 m is connected in series with 490 Ω resistance and 2 V battery. If 0.2 mV / cm is the potential gradient, then resistance of the potentiometer wire is (A) 4.9 Ω (B) 7.9 Ω (C) 5.9 Ω (D) 6.9 Ω

Tardigrade Admin · Accepted Answer

Pot. gradient =0.2 mV / cm =(0.2 × 10-3/10-2)=2 × 10-2 V / m Emf of cell =2 × 10-2 × 1 m =2 × 10-2 V =0.02 V As per the condition of potentiometer 0.02(R+490)=2(R) or 1.98 R=9.8 ⇒ R =(9.8/1.98)=4.9 Ω

Q. Potentiometer wire of length $1 m$ is connected in series with $490 Ω$ resistance and $2 V$ battery. If $0.2 mV / c m$ is the potential gradient, then resistance of the potentiometer wire is

$4.9Ω$

$7.9 Ω$

$5.9 Ω$

$6.9 Ω$

Q. Potentiometer wire of length 1m is connected in series with 490Ω resistance and 2V battery. If 0.2mV/cm is the potential gradient, then resistance of the potentiometer wire is

4.9Ω

7.9Ω

5.9Ω

6.9Ω

Pot. gradient =0.2mV/cm =10−20.2×10−3​=2×10−2V/m Emf of cell =2×10−2×1m =2×10−2V=0.02V As per the condition of potentiometer 0.02(R+490)=2(R) or 1.98R=9.8 ⇒R=1.989.8​=4.9Ω

Q. Potentiometer wire of length $1 m$ is connected in series with $490 Ω$ resistance and $2 V$ battery. If $0.2 mV / c m$ is the potential gradient, then resistance of the potentiometer wire is

$4.9Ω$

$7.9 Ω$

$5.9 Ω$

$6.9 Ω$