1.
A given wire has resistance R, now it's length is doubled while area gets halved then the new resistance of the wire will be
Correct Answer
A. Four times increases
Explanation
When the length of a wire is doubled, its resistance also doubles according to the formula R = ρL/A, where R is resistance, ρ is resistivity, L is length, and A is area. When the area of the wire is halved, the resistance becomes four times its original value. Therefore, the new resistance of the wire will be four times higher than its original resistance.
2.
A wire of resistance R, if it's length is doubles how does the Resistivity of the wire changes
Correct Answer
D. No change in Resistivity at all
Explanation
When the length of a wire doubles, the resistance of the wire also doubles. However, resistivity is an intrinsic property of the material and is independent of the dimensions of the wire. Resistivity is given by the formula ρ = R(A/L), where R is the resistance, A is the cross-sectional area, and L is the length of the wire. As the length doubles, the resistance doubles, but the cross-sectional area also doubles proportionally, resulting in no change in resistivity. Therefore, the correct answer is "No change in resistivity at all."
3.
Two wires connected to different batteries but of the same voltage if one wire is thicker than the other and current flows through both the wires for the same time, then which wire heats up more.
Correct Answer
A. The wire which is thinner will heats up more in comparison to wire which is thicker
Explanation
The wire which is thinner will heat up more because resistance is inversely proportional to the cross-sectional area of the wire. Thinner wires have higher resistance, causing more energy to be dissipated as heat. The thicker wire, with lower resistance, will have less energy dissipated as heat and therefore heat up less.
4.
Choose the correct statement:
Correct Answer
B. Resistance is directly propotional to temprature
5.
Choose the correct relationship from the following:
Correct Answer
A. H=VIT (wherevH= heat ,I= current ,V= potential Differece,T= time)
Explanation
The correct relationship is H = VIT, where H represents heat, I represents current, V represents potential difference, and T represents time. This equation is derived from the formula for calculating heat, which states that heat is equal to the product of current, potential difference, and time.
6.
Choose the correct statement:
Correct Answer
C. Direction of current is taken opposite to direction in which electrons are moving
Explanation
The correct statement is that the direction of current is taken opposite to the direction in which electrons are moving. This is because historically, when the concept of electric current was first introduced, it was not known that electrons were the actual charge carriers. Instead, it was believed that positive charges were moving. Therefore, the convention was established to consider the direction of current opposite to the actual movement of electrons. This convention is still followed today, even though we now know that electrons are the ones that carry the charge.
7.
The slope of Current versus Voltage graph tells us about:
Correct Answer
C. Reciprocal of resistance (1/R)
Explanation
The slope of the Current versus Voltage graph represents the ratio of the change in current to the change in voltage. In other words, it indicates how much the current changes for a given change in voltage. Since resistance is defined as the ratio of voltage to current (R = V/I), the reciprocal of resistance (1/R) is equal to the slope of the graph. Therefore, the slope of the Current versus Voltage graph tells us about the reciprocal of resistance (1/R).
8.
The correct unit for Potential Difference or Voltage is:
Correct Answer
A. Joule/Coulmb
Explanation
The correct unit for Potential Difference or Voltage is Joule/Coulomb. This unit represents the amount of work done (measured in Joules) in moving a unit of electric charge (measured in Coulombs) between two points in an electric circuit. It quantifies the energy transfer that occurs when electric charges move from a higher potential to a lower potential. The unit Ohm represents electrical resistance, while Joule and Coulomb are units of energy and charge respectively.
9.
Charge on a body is a:
Correct Answer
A. Scalar quantity
Explanation
Charge on a body is a scalar quantity because it only has magnitude and no direction. Scalar quantities are described by a single value or number, without any associated direction. In the case of charge, it can be positive or negative, but it does not have a specific direction in space. Therefore, it is considered a scalar quantity.