CURRENT ELECTRICITY

1. The speed at which the current travels in a conductor is nearly :

(A) 3 x 104 ms-1
(B) 3 x 106 ms-1
(C) 3 x 108 ms-1
(D) 3 x 1010 ms-1

Answer ⇒A


2. The resistance of a human body is about :

(A) 12 Ω
(B) 120 Ω
(C) 12 KΩ
(D) 120 MΩ

Answer ⇒C


3. The number of electrons that constitute 1 A of current is :

(A) 6.25 x 1016
(B) 6.25 x 1017
(C) 6.25 x 1018
(D) 6.25 x 1019

Answer ⇒C


4. How many different resistances are possible with two equal resistors ?

(A) 2
(B) 3
(C) 4
(D) 5

Answer ⇒B


5. Given three equal resistors, how many different combinations (taken all of them together) can be made ?

(A) 3
(B) 4
(C) 5
(D) 6

Answer ⇒B


6. Specific resistance of all metals is mostly affected by :

(A) temperature
(B) pressure
(C) magnetic field
(D) volume

Answer ⇒A


7. The example of a non-ohmic resistance is :

(A) copper wire
(B) filament lamp
(C) carbon resistor
(D) diode

Answer ⇒D


8. The length of a conductor is halved. Its resistance will be :

(A) halved
(B) doubled
(C) unchanged
(D) quadrupled

Answer ⇒A


9. In the above question, the conductance :

(A) halved
(B) doubled
(C) unchanged
(D) quadrupled

Answer ⇒B


10. Siemen is the unit of :

(A) resistance
(B) conductance
(C) specific conductance
(D) None of these

Answer ⇒B


11. Two wires of copper are of the same length but have different diameters. When they are connected in series across a battery, the heat generated is H1 When connected in parallel across the same battery, the heat generated during the same time is H2 Then :

(A) H1 = H2
(B) H1 < H2
(C) H1 > H2
(D) H1 > H2

Answer ⇒B


12. In questions 135, when the wires are connected in series, the heat produced in the thinner wire is H1 and that in the thicker wire is H2 Then :

(A) H1 = H2
(B) H1 < H2
(C) H1 > H2
(D) H1 ≥ H2

Answer ⇒C


13. Kirchhoff’s first and second laws for electrical circuits are consequences of :

(A) conservation of energy
(B) conservation of electrical charge and energy respectively
(C) conservation of electric charge
(D) neither conservation of energy nor electric charge

Answer ⇒B


14. A potential difference of 10 V is applied across a conductance of 2 S. The current in the conductor will be ;

(A) 20 A
(B) 5 A
(C) 0.2 A
(D) None of these

Answer ⇒A


15. Ohm’s law is valid when the temperature of conductor is :

(A) very low
(B) very high
(C) varying
(D) constant

Answer ⇒D


16. The emf of a car battery is about :

(A) 2.5 V
(B) 4.5 V
(C) 8.6 V
(D) 12 V

Answer ⇒D


17. Emf is measured in :

(A) joule
(B) joule/coulomb
(C) joule-coulombs
(D) joule/coulomb/metre

Answer ⇒B


18. 1 kilowatt hour is commonly known as:

(A) unit
(B) 1 faraday
(C) 1 curie
(D) None of these

Answer ⇒A


19. How many joules are equal to 1 kWh ?

(A) 3.6.x 104
(B) 3.6 x 105
(C) 3.6 x 106
(D) None of these

Answer ⇒C


20. Two bulbs 25 W, 220 V and 100 W, 220 V are given. Which has higher resistance ?

(A) 25 W
(B) 100 W
(C) both bulbs have equal resistance
(D) resistance of bulbs can not be compared

Answer ⇒A


21. In the following figure represents a balanced Wheatstone bridge circuit. What is the value of X ?

represents a balanced Wheatstone bridge circuit

(A) 15 Ω
(B) 20 Ω
(C) 25 Ω
(D) 30 Ω

Answer ⇒C


22. Potentiometer measures the potential difference more accurately than a voltmeter because :

(A) It has a wire of high resistance
(B) It has a wire of low resistance
(C) It does not draw current from external circuit
(D) It draws heavy current from external circuit

Answer ⇒C


23. The sequence of colour bands of a carbon resistance of 47 kΩ will be :

(A) yellow, violet, red
(B) yellow, violet, orange
(C) violet, yellow, orange
(D) red, red, violet

Answer ⇒B


24. The colour code for a resistance of 35 kΩ with 5% tolerance is :

(A) Orange, green, orange and gold
(B) Red, yellow, black and gold
(C) Orange, green, orange and silver
(D) Orange, green, red and gold

Answer ⇒D


25. In the figure, shows a wheatstone bridge circuit. Its 2 Acurrent enters A, then what is the current in the arm BC ?

current in the arm BC

(A) 3/2 A
(B) 1/2 A
(C) 2/3 A
(D) None of these

Answer ⇒A


26. The resistivity of a conductor depends upon its :

(A) length
(B) area of cross-section
(C) resistance
(D) None of these

Answer ⇒D


27. Internal resistance of a cell does not depend upon :

(A) electrode separation
(B) electrode material
(C) electrolyte
(D) electrolyte area

Answer ⇒D


28. For which of the following dependence of drit velocity Vd on electric field E is ohm’s law obeyed ?

(A) vd = √E
(B) vd ∝ E
(C) vd = E2
(D) vd = constant

Answer ⇒B


29. The voltage (V) and current (I) graph for a conductor at three different temperature T1, T2 and T3 are shown in the following figure. It follows:

graph for a conductor at three different temperature

(A) T1 > T2 > T3
(B) T1 = T2 = T3
(C) T1 < T2 < T3
(D) T1 = T2 ≈ T3

Answer ⇒A


30. If eight identical cells, each having an e.m.f. of 6V are connected in parallel, then the e.m.f. of the combination is :

(A) 1 V
(B) 1/8 V
(C) 48 V
(D) 6 V

Answer ⇒D


31. Which part of the curve shown in the fig. represents the negative resistance ?

represents the negative resistance

(A) AB
(C) CD
(B) BC
(D) DE

Answer ⇒C