Dakshana Mock Test Season VII Solutions

1] An electric current passes through a circuit containing two wires of the same material connected in parallel. If the lengths of the wires are in the ratio of 4:3 and radii of the wires are in the ratio of 2:3, then the ratio of the currents passing through the wires will be:

Answer: 1:3

2] The potential difference between points A and B of adjoining figure is:

Answer: 4V/3

3] From which of the following diagrams we can verify Ohm's law?

Answer: (i)

4] Find the reading of the ammeter given below.

Answer: 2V/3R

5] In the electric circuit shown below, the current through the 2.0Ω resistor is 3A. Approximately what is the EMF of the battery?

Answer: 42V

6] A thin solid conductor with sides PQRS is moving at constant velocity v, at right angles to a uniform magnetic field B, directed into the page as shown.

Which side of the conductor has the greatest concentration of electrons?

Answer: P

7] AB and CD are long straight conductors, distance between them is 'd'. State, the correct option about magnetic field on BC , if the current is flowing in AB and CD.

Answer: has different magnitudes at different points

8] A vertical wire carries a current upwards. The magnetic field at a point due north of the wire is directed

Answer: due west

9] A wire carrying a current 'I' is shaped as shown. Section AB is a quarter-circle of radius 'r'. The magnetic field at C is

Answer: perpendicular to the plane of paper, direction into the paper

10] A conductor AB of length 'l', carrying a current 'i' is placed perpendicular to a long straight conductor XY carrying a current I, as shown in the figure. The force on AB will act

Answer: Upward

11] In the figure, the resistance of rheostat 'R' is decreasing, then the brightness of the bulb 'B' will

Answer: Reduce

12] Two wires of the same metal has the same length but their cross-sections are in the ratio 3:1. They are joined in series. The resistance of of the thicker wire is 10Ω. The total resistance of the combination will be

Answer: 40Ω

13] In this circuit shown the reading of ammeter is 2A. This ammeter has negligible resistance. The value of R equals

Answer: 6Ω

14] In the network, the current flowing through the resistance R shown in the figure is

Answer: 3E/7R

15] If a wire is stretched to make it 0.1% longer. The percentage change in its resistance would be

Answer: 0.2%

16] The reading of ammeter as per figure shown is

Answer: 3A/4

17] An infinite ladder network is constructed with 1Ω and 2Ω resistor as shown. The effective resistance between A and B is

Answer: 2Ω

18] Two identical heater wires of equal length are first connected in series and then in parallel, the ratio of

Answer: the heat produced in them is 1:4

19] The resistivity of conductor in the form of a wire depends on its

Answer: material

20] A steady current flows in a metallic conductor of non uniform cross-section. Which of the following quantities remain constant along the length of the conductor?

Answer: Current

21] In the circuit shown in figure the rate of heat produced in the 5Ω resistance is 20Js^-1. Choose the correct option based on the statements and figure.

Answer: The rate of heat produced in the 4Ω resistor is 4Js^-1

22] Figure shows a network of currents. The magnitude of currents is shown here. The current 'I' will be

Answer: 20A

23] A helium nucleus makes a full rotation in a circle of radius 0.8 metre in two seconds. The value of the magnetic field B at the centre of the circle will be

Answer: 10^-19μ₀

24] The magnetic induction at the center O in the figure shown is