HSSC-II (Class-12) Solved Physics MCQs; Unit-12: Current Electricity (Baluchistan Textbook Board, Quetta) With Verified Answers 

1. A flow of 10⁷ electrons per second through a conductor produces a current of




... Answer is A. 1.6 ｘ 10⁻¹² A
I = `\frac {Q}{t}` where Q = ne = 10⁷ ｘ1.6 ｘ 10⁻¹⁹C and t = 1 s


2. The first source of e.m.f. was discovered by




... Answer is B. Volta
Alessandro Volta (in 1800s),


3. Which one of the given cells is not rechargeable?




... Answer is A. Laclanche
The Laclanche is a primary cell and cannot easily be recharged after one use.


4. Which one of the given sources converts light energy into electrical energy?




... Answer is C. Photocell
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5.  Which one of the following materials is non-ohmic:




... Answer is B. Germanium
Metals are ohmic and Semiconductors and insulators are non Ohmic materials


6. What will be the resistance of the wire when its length is doubled




... Answer is C. Double
Formula for Resistance R = `\frac {ρl}{A}`


7. If the resistivity of the conductor is 2 ｘ 10⁶ Ω m then its conductivity is :




... Answer is D. 5 ｘ 10⁵ Ω⁻¹ m⁻¹
resistivity and conductivity are inversely related ie. σ = `\frac {1}{ρ}`


8. Siemen is a unit of conductance and it is equal to




... Answer is D. mho . m⁻¹
Conductance G = `\frac {1}{R}` = Ω⁻¹ = mho = Siemen


9. When the resistance of the material increases by increasing the temperature than the value of the coefficient of resistivity will be




... Answer is C. Positive
co-efficient of resistivity 𝞪 is Positive for materials like copper, silver, tungsten, etc whose resistance increases by increasing temperature, and negative for that materials like germanium, silicon whose resistance decreases by increasing temperature.


10. The unit of temperature co-efficient is




... Answer is B. °C⁻¹
ΔR = 𝞪 R₀ ΔT


11. In the presence of internal resistance of the source, which one of the following relations between the potential difference (V) and e.m.f. (E) is correct




... Answer is C. E > V
E = IR + Ir = V + Ir this means E > V


12. The unit of electromotive force is




... Answer is D. Volt
e.m.f is a special type of potential difference known as electromotive force (emf). The emf is not a force.


13. The source of e.m.f. transfers its maximum power to the external circuit when (r = internal resistance, R = load resistance)

... Answer is B. r = R
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14.  Kirchhoff's 1st law is based upon the law of conservation of




... Answer is B. Charge
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15. The node in an electric circuit that has zero potential is known as




... Answer is D. Datum node
Zero potential is known as the Datum node


16.. When the direction of current is from the negative to positive terminal of the battery then 'E' is taken as




... Answer is C. Positive
When the current direction is from the negative to positive terminal of the battery there is a rise in potential and E is taken positive and vice versa.


17. If the current passes through a resistor in an anticlockwise direction. Then the electric potential will be :




... Answer is C. Raised
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18. An electrical device that controls the current is known as




... Answer is B. Rheostat
-----Check definition


19. The electrical device which is being used to compare the e.m.f. of two cells is known as




... Answer is C. Potentiometer
Check definition






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