# Uncle n Aunty ,Clock n Anti

Electricity and Magnetism Level 4

On a frictionless horizontal tabletop is held at rest a rigid square loop of side length L carrying an electric current with some mechanism.A uniform magnetic field pointing upwards to the leftof the dashed lines shown in the figure is switched on and then the loop is released. Consider different segments of side segments x and y

$$x\lneq y$$ then find the sum of numbers of corresponding incorrect answers.

a) If $$x\lneq\frac{L}{2}$$ and $$y=\frac{L}{2}$$ the loop starts rotating anticlockwise.$$\rightarrow2$$

b) If $$x\lneq\frac{L}{2}$$ and$$y\lneq\frac{L}{2}$$ the loop starts rotating anticlockwise $$\rightarrow3$$

c)If $$x\lneq\frac{L}{2}$$ and $$y\gneq\frac{L}{2}$$ the loop starts rotating clockwise $$\rightarrow5$$

d)If $$x\lneq\frac{L}{2}$$ and $$y\gneq\frac{L}{2}$$ more information is required to decide which way the loop starts rotating.$$\rightarrow7$$

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