1.
What is the amount of current flowing through an electric press, if the amount of charge passing through a conductor in 10 minutes is 300 C?
Correct Answer
C. 0.5A
Explanation
The amount of current flowing through an electric press can be determined by dividing the amount of charge passing through the conductor by the time taken. In this case, the amount of charge passing through the conductor is given as 300 C and the time taken is 10 minutes. Dividing 300 C by 10 minutes gives us 30 C/min. Since 1 Ampere (A) is equal to 1 C/min, the amount of current flowing through the electric press is 0.5 A.
2.
Keeping the potential difference constant, the resistance of the circuit is halved. The current will become:
Correct Answer
D. Double
Explanation
When the resistance of a circuit is halved while keeping the potential difference constant, according to Ohm's Law (V = IR), the current (I) will double. This is because the equation states that the current is directly proportional to the potential difference and inversely proportional to the resistance. Therefore, if the resistance decreases by half, the current will increase by a factor of two.
3.
The resistance whose V-I graph is given below is
Correct Answer
B. 3/5 ohm
Explanation
The V-I graph shows a straight line passing through the origin with a positive slope. This indicates that the resistance is constant and does not change with the current. The slope of the line can be determined by calculating the ratio of the change in voltage to the change in current. In this case, the slope is 3/5, which represents the resistance. Therefore, the correct answer is 3/5 ohm.
4.
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
Correct Answer
A. 10^{20}
Explanation
The current of 1 A represents the flow of 1 coulomb of charge per second. Since the charge of one electron is 1.6 x 10^-19 coulombs, the number of electrons passing through the filament in 16 seconds can be calculated by multiplying the current (1 A) by the time (16 seconds) and dividing by the charge of one electron. Therefore, the approximate number of electrons passing through the filament in 16 seconds would be 1 x 16 / (1.6 x 10^-19) = 1 x 10^19 / (1.6 x 10^-19) = 10^20 / 1.6 ≈ 1020.
5.
The resistivity does not change if
Correct Answer
C. The shape of the resistor is changed
Explanation
The resistivity of a material is an intrinsic property that does not depend on the shape of the resistor. Resistivity is a measure of how strongly a material opposes the flow of electric current, and it is determined by the material's composition and structure. Changing the shape of the resistor may affect its resistance, but it does not alter the resistivity of the material itself.
6.
Electric potential is a:
Correct Answer
A. Scalar quantity
Explanation
Electric potential is a scalar quantity because it only has magnitude and no direction. Scalar quantities are described by a single value, such as temperature or mass, and do not have any associated direction. In the case of electric potential, it represents the amount of electric potential energy per unit charge at a given point in an electric field. The magnitude of electric potential can be measured, but it does not have a specific direction associated with it.
7.
1 mV is equal to:
Correct Answer
C. 10^{-3}V
Explanation
1 mV is equal to 10-3V. The prefix "m" in mV stands for milli, which represents a factor of 10-3. This means that 1 mV is equal to 0.001V or 10-3V.
8.
When electric current is passed, electrons move from:
Correct Answer
B. Low potential to high potential.
Explanation
When electric current is passed, electrons move from low potential to high potential. This is because electrons are negatively charged particles and are attracted to positively charged regions. Therefore, they tend to move towards areas of higher electric potential, which corresponds to higher positive charge.
9.
The electrical resistance of insulators is
Correct Answer
D. Infinitely high
Explanation
Insulators are materials that do not conduct electricity easily. They have a high resistance to the flow of electric current. This means that it is difficult for the electrons to move through the insulator, resulting in a high electrical resistance. As a result, the correct answer is "infinitely high" because insulators effectively prevent the flow of electric current.
10.
Which of the following is not correctly matched?
Correct Answer
C. C
Explanation
The answer "c" is not correctly matched because it does not correspond to any of the options given in the question. The question asks for a match, but option "c" does not have a corresponding match.
11.
Current is a _______ quantity
Correct Answer
Scalar
Explanation
Current is a scalar quantity because it only has magnitude and no direction. Scalar quantities are described by a single value, such as mass or temperature, and do not involve any directional components. In the case of current, it is simply the flow of electric charge through a conductor and is measured in amperes (A).
12.
Diode follows Ohm's law
Correct Answer
B. False
Explanation
Diodes do not follow Ohm's law. Ohm's law states that the current flowing through a conductor is directly proportional to the voltage applied across it, and inversely proportional to its resistance. However, diodes are non-linear devices and their current-voltage relationship is not linear like that of resistors. Diodes have a forward voltage drop and exhibit exponential behavior when conducting current. Therefore, the statement that diodes follow Ohm's law is false.
13.
SI unit of resistivity
Correct Answer
C. Ohm metre
Explanation
The SI unit of resistivity is ohm metre. Resistivity is a measure of how strongly a material opposes the flow of electric current. It is a property of the material itself and is independent of its dimensions. The unit ohm metre represents the resistance of a one-metre-long conductor with a cross-sectional area of one square metre. It is commonly used to quantify the resistance offered by various materials and is an important parameter in electrical and electronic applications.
14.
A torch bulb is rated at 1.5 V, 500 mA. Find its resistance.
Correct Answer
B. 3 ohm
Explanation
The resistance of the torch bulb can be found using Ohm's Law, which states that resistance (R) is equal to voltage (V) divided by current (I). In this case, the voltage is given as 1.5 V and the current is given as 500 mA (which is equivalent to 0.5 A). By dividing the voltage by the current (1.5 V / 0.5 A), we get a resistance of 3 ohms. Therefore, the correct answer is 3 ohm.
15.
Temperature depends on resistance indirectly
Correct Answer
B. False
Explanation
Resistance and temperature are directly related, not indirectly. As resistance increases, temperature also increases. This is due to the fact that as the temperature of a material increases, the atoms within the material vibrate more vigorously, leading to more collisions between the electrons and the atoms. These collisions impede the flow of electrons, causing an increase in resistance. Therefore, the correct answer is False.