1.
An electrical appliance has a resistance of 25 Ω. When this electrical appliance is connected to a 230 V supply line, the current passing through it will be:
Correct Answer
C. 9.2A
Explanation
When an electrical appliance is connected to a supply line, the current passing through it can be calculated using Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). In this case, the resistance of the appliance is given as 25 Î© and the voltage of the supply line is 230 V. By substituting these values into the formula, we can calculate the current passing through the appliance as 230 V / 25 Î© = 9.2 A. Therefore, the correct answer is 9.2A.
2.
In the given figure, the resistors:
Correct Answer
D. 3 Ω and 6 Ω are in parallel and the combination is in series with 9 Ω
Explanation
The given figure shows a combination of resistors connected in series and parallel. According to the given information, the 3 Î© and 6 Î© resistors are connected in parallel, and this combination is connected in series with the 9 Î© resistor. This means that the current flowing through the 3 Î© and 6 Î© resistors is the same, and the total resistance of this combination is the sum of the resistances of the individual resistors. Finally, this combination is connected in series with the 9 Î© resistor, which means that the total resistance of the circuit is the sum of the resistances of all the resistors in the circuit.
3.
Electric power is inversely proportional to:
Correct Answer
A. Resistance
Explanation
Electric power is inversely proportional to resistance because as resistance increases, the flow of electric current decreases. This decrease in current leads to a decrease in power, as power is calculated by multiplying the current by the voltage. Therefore, when resistance increases, the power output decreases.
4.
Three resistors of 1 â„¦, 2 ohms,s, and 3 â„¦ are connected in parallel. The combined resistance of the three.
Correct Answer
B. Less than 2â„¦
Explanation
When resistors are connected in parallel, the total resistance decreases. This is because the current has multiple paths to flow through, reducing the overall resistance. In this case, the resistors of 1 â„¦, 2 â„¦, and 3 â„¦ are connected in parallel. The total resistance will be less than the smallest individual resistance, which is 1 â„¦ in this case. Therefore, the combined resistance of the three resistors will be less than 2 â„¦.
5.
Point to be kept in mind for verification of Ohm’s Law is:
Correct Answer
B. Ammeter should be connected in series and voltmeter in parallel
Explanation
To verify Ohm's Law, the ammeter should be connected in series and the voltmeter should be connected in parallel. This is because the ammeter is used to measure the current flowing through the circuit, which requires it to be connected in series with the component being measured. On the other hand, the voltmeter is used to measure the voltage across the component, which requires it to be connected in parallel to measure the potential difference. By connecting the ammeter in series and the voltmeter in parallel, accurate measurements of current and voltage can be obtained to verify Ohm's Law.
6.
There is the wire of length I and cross-section A. Which of the given have the least resistance.
Correct Answer
C. Length halved, Area doubled
Explanation
When the length of the wire is halved, the resistance decreases because resistance is directly proportional to length. On the other hand, when the area is doubled, the resistance decreases because resistance is inversely proportional to cross-sectional area. Therefore, when the length is halved and the area is doubled, the resistance decreases the most compared to the other options.
7.
A car headlight bulb working on a 12 V car battery draws a current of 0.5 A. The resistance of the light bulb is:
Correct Answer
B. B. 6 Ω
Explanation
The resistance of the light bulb can be calculated using Ohm's Law, which states that resistance is equal to voltage divided by current. In this case, the voltage is 12 V and the current is 0.5 A. Therefore, the resistance is 12 V / 0.5 A = 24 Î©.
8.
The resistance of a conductor depends directly on its ……… and ...... , inversely on its ………
Correct Answer
Resistivity, length,Area
Explanation
The resistance of a conductor depends directly on its resistivity, length, and inversely on its area. Resistivity is a property of a material that determines how strongly it resists the flow of electric current. The longer the conductor, the greater the resistance because there is more material for the current to pass through. Similarly, the smaller the cross-sectional area of the conductor, the greater the resistance because there is less space for the current to flow through. Therefore, the resistance of a conductor is directly proportional to resistivity and length, and inversely proportional to area.
9.
According to ohm's Law, the ............ across the ends of a resistor is directly proportional to the ……… flowing through it, provided its ...........
remains constant.
Correct Answer
Potential difference, Current.Temperature
Explanation
Ohm's Law states that the potential difference (voltage) across the ends of a resistor is directly proportional to the current flowing through it, as long as the resistance remains constant. Temperature is not a factor in Ohm's Law. Therefore, the correct answer is potential difference and current.
10.
If the amount of electric charge passing through a conductor in 10 minutes is 300 C, the current flowing is:
Correct Answer
B. 0.5A
Explanation
The amount of electric charge passing through a conductor is directly proportional to the current flowing through it and the time for which the current flows. In this case, the given information states that the amount of electric charge passing through the conductor in 10 minutes is 300 C. Since the current is given by the equation I = Q/t, where I is the current, Q is the amount of charge, and t is the time, we can substitute the given values to find the current. Therefore, the current flowing through the conductor is 300 C / 10 minutes = 30 C/min = 0.5 A.
11.
An electric fuse works on the:
Correct Answer
D. Heating effect of current
Explanation
An electric fuse works on the heating effect of current. When excessive current flows through a circuit, the fuse wire heats up due to its resistance. This excessive heat causes the fuse wire to melt and break the circuit, protecting the other components from damage. The heating effect of current is utilized in electric fuses to provide a safety mechanism and prevent electrical fires or damage to the electrical system.
12.
From the graph:
Correct Answer
D. Resistance
13.
Calculate Resistance.
Correct Answer
D. 15 Ω
Explanation
The answer is 15 Î© because it is the only resistance value provided in the options.
14.
If in the given arrangement, the three resistors are to be replaced by a single resistor. What will be the value of this resistor?
Correct Answer
D. 9Ω
Explanation
The value of the single resistor that will replace the three resistors in the given arrangement will be 9Î©. This is because when resistors are connected in parallel, the total resistance is the reciprocal of the sum of the reciprocals of the individual resistances. In this case, the reciprocal of 6Î©, 18Î©, and 12Î© is 1/6 + 1/18 + 1/12 = 1/9. Taking the reciprocal of 1/9 gives 9Î©, which is the value of the single resistor.
15.
In An Electrical Circuit Three Incandescent Bulbs A, B And C Of Rating 40 W, 60 W And 100 W Respectively Are Connected In Parallel To An Electric Source. Which Of The Following Is Likely To Happen Regarding Their Brightness?
Correct Answer
C. Bulb C glows with more brightness than A and B
Explanation
In a parallel circuit, each bulb receives the same voltage from the electric source. However, the brightness of a bulb is determined by its power rating, with higher power bulbs appearing brighter. In this case, bulb A has a power rating of 40 W, bulb B has a power rating of 60 W, and bulb C has a power rating of 100 W. Therefore, bulb C, being the bulb with the highest power rating, will glow with more brightness than bulbs A and B.
16.
When a current 'I' flows through a resistance 'R' for time 't' the electrical energy spent is given by:
Correct Answer
A. I ^{2} Rt
Explanation
The correct answer is I^2Rt. This formula is derived from the equation for electrical power, P = IV, where P represents power, I is the current, and V is the voltage. By rearranging the equation to solve for V, we get V = IR. The electrical energy spent is given by the product of power and time, E = Pt. Substituting V = IR into the equation, we get E = I(IR)t, which simplifies to E = I^2Rt. Therefore, the correct answer is I^2Rt.
17.
Which one connected properly?
Correct Answer
A. Ii
18.
The resistance of a conductor increases with-
I: Increase in length
II: Increase in volume
III: Decrease in area
iv: Temperature
Correct Answer
B. I&III
Explanation
The resistance of a conductor increases with an increase in length because a longer conductor provides more opposition to the flow of current. The resistance also increases with a decrease in area because a smaller cross-sectional area restricts the flow of electrons. However, the resistance does not depend on the volume of the conductor. Temperature also affects the resistance, as it increases the resistance of most conductors. Therefore, the correct answer is I & III, as both an increase in length and a decrease in area contribute to an increase in resistance.
19.
The rheostat is used in the circuit to :
Correct Answer
C. increase or decrease the magnitude of current
Explanation
The rheostat is a variable resistor that can be used to control the amount of current flowing through a circuit. By adjusting the position of the rheostat, the resistance in the circuit can be increased or decreased, which in turn affects the magnitude of the current. Therefore, the rheostat can be used to either increase or decrease the magnitude of current flowing through the circuit, depending on the desired application.
20.
The total resistance?
Correct Answer
A. 9 Ω
Explanation
The total resistance is 9 Î© because it is the only value provided in the list.
21.
The work done to Move a unit charge from one point to another point is called?
Correct Answer
C. Potential difference
Explanation
Potential difference refers to the work done to move a unit charge from one point to another. It is a measure of the energy transferred per unit charge, and is commonly referred to as voltage. When a charge is moved against an electric field, work is done on the charge, and this work is equal to the potential difference between the two points. Therefore, potential difference is the correct answer for the given question.
22.
SI unit of electrical Potential Difference is Ampere (A).
Correct Answer
B. False
Explanation
The given statement is incorrect. The SI unit of electrical Potential Difference is Volt (V), not Ampere (A). Ampere is the unit of electric current, while Volt is the unit of potential difference or voltage.
23.
The commercial unit of electric power.
Correct Answer
B. Kilo watt hour
Explanation
The correct answer is "Kilo watt hour." The question is asking for the commercial unit of electric power, and the kilo watt hour is commonly used in commercial settings to measure the amount of energy consumed or produced over a period of time. It is a unit of electrical energy equal to one kilowatt of power expended for one hour.
24.
We prefer parallel connection over series connection because:
Correct Answer
B. It offers less resistance and all the device work properly
Explanation
Parallel connection is preferred over series connection because it offers less resistance. In a parallel connection, each device has its own separate path for current flow, resulting in a lower overall resistance compared to a series connection where the resistance of each device adds up. With less resistance, the electrical devices connected in parallel can work properly as they receive the required amount of current.
25.
The relation between potential difference v and electrical current I given by:
Correct Answer
A. Ohm's law
Explanation
Ohm's law states that the potential difference (voltage) across a conductor is directly proportional to the current flowing through it, when the temperature and other physical conditions remain constant. Therefore, Ohm's law is the correct answer as it describes the relationship between potential difference (v) and electrical current (I).