CBSE
For the post office box arrangement to determine the value of unknown resistance, the unknown resistance should be connected between
B and C
C and D
A and D
B1 and C1
Which of the following graphs represent variation of magnetic field B with distance r for a straight long wire carrying current ?
A uniform wire of resistance R and length L is cut into four equal parts, each of length L/4, which are then connected in parallel combination. The effective resistance of the combination will be
R
4R
Which of the following set up can be used to verify the Ohm's law ?
Two identical cells of the same emf and same internal resistance give the same current through an external resistance 22, regardless of whether they are connected in series or parallel. The internal resistance of the cell is
1 Ω
2 Ω
3 Ω
4 Ω
In the given circuit the equivalent resistance between the points A and B in ohms is
9
11.6
14.5
21.2
Six equal resistance are connected between points P, Q and R as shown in the figure. Then the net resistance will be maximum between
P and Q
Q and R
P and Q
only two points
The equivalent resistance across A and B is
2 Ω
3 Ω
4 Ω
5 Ω
In the electric circuit shown each cell has an emf of 2 V and internal resistance of 1Ω. The external resistance is 2Ω. The value of the current I is (in amperes)
2
1.25 Ω
0.4
1.2
The figure shows variation of photocurrent with anode potential for a photo- sensitive surface for three different radiations. Let Ia , lb and Ic be the intensities and va , vb and vc , be the frequencies for the curves a, b and c respectively. Then
va = vb and Ia ≠ Ib
va = vc and Ia = Ic
va = vb and Ia = Ib
vb = vc and Ib = Ic