10 Question-Answer on OHM and Kirchhoff law
1. The V – I graph of a good conductor makes angle 40˚ with V-axis. Here V denotes voltage and I denote current. The resistance of the conductor will be
(a) Sin 40˚
(b) Cos 40˚
(c) Tan 40˚
(d) Cot 40˚
Ans: (d)
2. When potential difference is applied across an electrolyte, then ohm’s law is obeyed at
(a) Zero potential
(b) Very low potential
(c) Negative potential
(d) High potential
Ans: (d)
3. When the potential difference applied across a solid conductor is increased, the rate of flow of electrons
(a) Remains same
(b) Decreases
(c) Increases
(d) Decreases sharply
Ans: ( c)
4. Kirchhoff’s first law i.e. ∑ I =0 at a junction, deals with the conservation of
(a) Charge
(b) Energy
(c) Momentum
(d) All of these
Ans: ( a)
5. Kirchhoff’s second law is related to:
(a) Law of conservation of energy
(b) Law of conservation of momentum
(c) Lenz’s law
(d) Faraday’s second law of electrolysis
a
6. According to the Kirchoff’s law the algebraic sum of the products of current and resistance as well as e.m.f. in a close loop is:
(a) Zero
(b) Greater than zero
(c) Less than zero
(d) To be decided by the e.m.f.
Ans: (a)
7. Twelve identical wires each of resistance 6Ω are arranged to form a Skelton cube. A current of 40 mA is led into cube at one corner and out at the other corner of the same edge of the cube. The effective resistance between the corners of the same edge of cube is:
(a) 5Ω
(b) 3.5 Ω
(c) 8.5 Ω
(d) None of above
Ans: (b)
8. In the above question, the potential difference developed between the corners of the same edge of the cube will be:
(a) 0.2 V
(b) 0.40 V
(c) 0.14 V
(d) 0.34 V
Ans: (c)
9. A wire of resistance 6Ω is cut into three equal pieces, which are joined to form a triangle. The equivalent resistance between any two corners of the triangle is:
(a) (3/4)Ω
(b) (4/3)Ω
(c) 2Ω
(d) 4Ω
Ans: (b)
10. Two resistances are joined in parallel whose resistance is 3/5 Ω. One of the resistance wire is broken and the effective resistance becomes 3 Ω. The resistance in ohm of the wire that got broken was :
(a) 4/3
(b) 2
(c) 6/5
(d) ¾
Ans: (d)