Current Electricity
Current Electricity
Top questions
See all →- In a metre bridge, a 2 Ω resistance is in the left gap and an unknown resistance \(X\) in the right gap. The null point is at 40 cm from the left end. Then \(X\) is Answer: D. 3 Ω 2/X=40/60⇒ X=3\ Ω . 1
- A potentiometer wire 4 m long of resistance 8 Ω is connected in series with a 12 Ω resistor and a 2 V cell of negligible internal resistance. The balancing length for a cell of emf 0.5 V is Answer: C. 2.5 m I=2/20=0.1 A; potential gradient =0.1×8/4=0.2 V/m; l=0.5/0.2=2.5 m. 1
- A galvanometer of resistance 50 Ω gives full-scale deflection for 5 mA. The shunt needed to convert it into an ammeter of range 0–5 A is approximately Answer: D. 0.05 Ω S=I_gG/I-I_g=0.005×50/4.995≈0.05\ Ω . 1
- Kirchhoff’s first law, i.e., ΣI = 0 at a junction, deals with the conservation of (A) charge Kirchhoff’s first law, i.e., ΣI = 0 at a junction, deals with the conservation of charge 1
- When the balance point is obtained in the potentiometer, a current is drawn from Answer: (C) auxiliary battery only In a potentiometer, the auxiliary battery (driver cell) is connected across the potentiometer wire and ke... 1
- Define Potential Gradient. Potential gradient is defined as the potential difference (the fall of potential from the high potential end) per unit length of the wire. 1