CBSE X Science Effects of Current - EducareHut (Next Gen Knowledge Point)

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#1. When electric current is passed, electrons move from:

high potential to low potential.

low potential to high potential.

in the direction of the current.

against the direction of the current

#2. To get 2 Ω resistance using only 6 Ω resistors, the number of them required is

Explanation: (b) Three resistors of 2 Ω is required to get 6 Ω because resultant is more than individual so they all must be connected in series.

#3. 1 kWh = ……….. J

3.6 × 10^-6 J

13.6 × 10^6 J

3.6 × 10^6 J

13.6 × 10^-6 J

#4. Electrical resistivity of any given metallic wire depends upon

its thickness

its shape

nature of the material

its length

#5. The resistance whose V-I graph is given below is

Explanation: (b) Resistance = slope line of V-I graph =

(9-0)/(15-0)=9/15=3/5

#6. Which of the following represents voltage?

Work done /(Current x Time)

Word done x Charge

(Work done x Time) / Current

Work done x Charge x Time

#7. A student carries out an experiment and plots the V ‒ I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively as shown in figure. Which of the following is true?

R1 = R2 = R3

R1 > R2 >R3

R3 > R2 > R1

R2 > R3 > R1

Explanation: Slope of VI graph is proportional to 1/ Resistance.

It means when slope will be maximum, then resistance will be minimum.

From the figure, we can see that, slope of R1 is maximum; hence its resistance will be minimum.

As, slope of R3 is minimum so, its resistance will be maximum.

Therefore, R3 > R2 > R1

#8. What is the maximum resistance which can be made using five resistors each of 1/5 Ω?

1/5 Ω

10 Ω

5 Ω

1 Ω

Explanation: The maximum resistance is obtained when resistors are connected in series combination.

Thus equivalent resistance obtained by connecting five resistors of resistance 1/5 Ω each, in series = (1/5 1/5 1/5 1/5) = 1 Ω

#9. Which of the following gases are filled in electric bulbs?

Helium and Neon

Neon and Argon

Argon and Hydrogen

Argon and Nitrogen

#10. 1 mV is equal to:

10 volt

1000 volt

10^-3 volt

10^-6 volt

#11. In an electrical circuit, two resistors of 2 and 4 respectively are connected in series to a 6V battery. The heat dissipated by the 4 resistor in 5s will be

10J

20J

30J

Explanation:

Here, first resistor, R1 = 2Ω

And second resistor, R2 = 4Ω

Voltage of cell, V = 6V

Time taken = t = 5s

Total resistance of the circuit = R = R1 R2 = 2 4 = 6 Ω

Current, I = V/R = 6/6 = 1A

Heat dissipated by the 4Ω resistor in 5s is given as,

H = I²Rt

⟹ H = 1 x 1 × 4 × 5 = 20J

#12. Electrical resistivity of a given metallic wire depends upon

Its length

Its thickness

Its shape

Nature of the material

Explanation: The resistivity of a material is constant for a particular temperature at a constant temperature.
Resistivity of material does not depend on length, thickness and shape of the material. It only depends on the temperature.

#13. A cell, a resistor, a key, and an ammeter are arranged as shown in the circuit diagrams. The current recorded in the ammeter will be

maximum in (i)

maximum in (ii)

maximum in (iii)

same in all the cases

Explanation :(d) Ammeter is always connected in series with in the circuit. The reading is independent from its location.

#14. A battery of 10 volt carries 20,000 C of charge through a resistance of 20 Ω. The work done in 10 seconds is

2 × 10^3 joule

2 × 10^5 joule

2 × 10^4 joule

2 × 10^2 joule

Explanation: (b) W= qV= 20000 × 10 = 2,00,000 = 2 × 10⁵ J

#15. What is the commercial unit of electrical energy?

Joules

Kilojoules

Kilowatt-hour

Watt-hour

#16. Electric power is inversely proportional to

resistance

voltage

current

temperature

#17. In the following circuits, heat produced in the resistor or combination of resistors connected to a 12 V battery will be

Same in all the cases

Maximum in case (i)

Maximum in case (ii)

Maximum in case (iii)

#18. Two wires of same length and area, made of two materials of resistivity ρ1 and ρ2 are connected in parallel V to a source of potential. The equivalent resistivity for the same length and area is

Explanation: (b) Equivalent resistance in parallel combination is

1/R_P =1/R₁ 1/R₂

For the same length and area of cross-section, R ∝ p (resistivity)

#19. A cylindrical conductor of length l and uniform area of cross section A has resistance R. Another conductor of length 2l and resistance R of the same material has area of cross-section.

A/2

3A/2

Resistivity of first conductior = (RA/l)
Resistivity of second conductor = (RA’/2l)

Resistivity of both material is same
so (RA)/(l) = (RA’/2l) => A’=2A

#20. A current of 1 A is drawn by a filament of an electric bulb. Number of electron passing through a cross-section of the filament in 16 seconds would be roughly

10^20

10^16

10^18

10^23

Current i= 1 A, time t=16s
Nuber of electrons=n
i=Q/t=ne/t
n=it/e=(1X16)/ (1.6*10^-19)=10^20

#21. A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly

10^20

10^16

10^18

10^23

Explanation: (a) Q = ne and Q = It

∴ ne = It

n=IT/e= (1×16)/(1.6×10^-19)

10²⁰

#22. The resistivity of insulators is of the order of

10^-8 Ω-m

10^1 Ω-m

10^-6 Ω-m

10^6 Ω-m

#23. Calculate the current flows through the 10 Ω resistor in the following circuit

1.2 A

0.6 A

0.2 A

2.0 A

Explanation: (b) In parallel, potential difference across each resistor will remain same. So, current through 10-Ω resistor

I = V/R=6/10 = 0.6 A

#24. Two resistors of resistance 2 and 4 when connected to a battery will have

same current flowing through them when connected in parallel

same current flowing through them when connected in series

same potential difference across them when connected in series

different potential difference across them when connected in parallel

Explanation: In series combination of resistor, the current through both the resistor are same but potential difference across each will be different.

In parallel combination, current across each resistor will be different but the potential difference will be same.

#25. A cell, a resistor, a key and an ammeter are arranged as shown in the circuit diagrams of figure. The current recorded in the ammeter will be

Maximum in (i)

Maximum in (ii)

Maximum in (iii)

The same in all the cases

Explanation: In series connections the order of elements in the circuit will not affect the amount of current flowing in the circuit.

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