As shown in Figure 11, half of a rectangular coil ABCD with an area of S is in a uniform magnetic field with a magnetic induction intensity of B. at this time, the magnetic flux passing through the coil is WB

As shown in Figure 11, half of a rectangular coil ABCD with an area of S is in a uniform magnetic field with a magnetic induction intensity of B. at this time, the magnetic flux passing through the coil is WB

As shown in the figure, when half of the rectangular coil ABCD is in a uniform magnetic field with a magnetic induction of B
The magnetic flux is Φ 1 = B & # 8226; 1 / 2 s = 1 / 2 BS
When the coil rotates 60 ° from the position in the figure with ab as the axis, the projected area of the coil perpendicular to the magnetic field is 1 / 2S
Then the magnetic flux Φ 2 = B &; 1 / 2S = 1 / 2BS
So the answer is: 1 / 2BS; 1 / 2BS

In the uniform magnetic field with B = 0.5T, there is a square metal coil ABCD with L = 0.2m
In the uniform magnetic field with magnetic induction intensity B = 0.5T, there is a square metal coil and a square metal coil ABCD with side length L = 0.2m. The side of the coil ad coincides with the left boundary of the magnetic field, and the resistance of the coil is 0.4 Ω. External force is used to make the coil move out of the magnetic field: once, force is used to make the coil move out of the magnetic field at a uniform speed from the left boundary, In the other time, the coil is forced to rotate at a constant speed with AD as the axis, and the time taken for two times is 0.1s?

When the coil moves out of the magnetic field uniformly from the left boundary, the induced electromotive force generated in the coil is e = Δ φ / Δ t = 0.5 × 0.2 × 0.2 / 0.1 = 0.2V, the current is I = E / r = 0.2 / 0.4 = 0.5A, f = bil = 0.5 × 0.5 × 0.2 = 0.05N, W1 = f × L = 0.05 × 0.2 = 0.01j;
When the coil rotates uniformly on the axis ad, the induced electromotive force is e = Δ φ / Δ t = 0.5 × 0.2 × 0.2 / 0.1 = 0.2V, the current is I = E / r = 0.2 / 0.4 = 0.5af = bil = 0.5 × 0.5 × 0.2 = 0.05N, W2 = f × L = (0.05 × 2 π / 4) × 0.2 = 0.0157j;
The difference of work done by two external forces is Δ w = W1-W2 = 0.01-0.0157 = -0.0057j

24. As shown in Figure 8, when a closed rectangular coil ABCD is placed in a sufficiently large uniform magnetic field, which of the following conditions can induce current in the coil
A. Coil translation to the left
C. The coil rotates on the axis ab. the coil does not move
Question 24 of 2009 Guangdong senior high school proficiency test

If you can't see the figure, guess that it should be C. There should be a closed loop and a change in the magnetic flux in the loop to generate the induced current. Guess that the direction of B should be the same as or opposite to the direction of the magnetic field, and there is no induced current because it doesn't cut the magnetic induction line, D, not to mention. But in case a, there is an induced potential on a certain section of wire. Because there is no picture, I guess like this