4. A student creates a home-made solenoid by wrapping copper wire around a toilet paper dispenser. As shown below, when attached to a power supply of fixed voltage, the solenoid produces a magnetic field within it of 840 x 10 T. = + a) Based on the polarity of the power supply, use the Right-Hand-Rule to determine the north and south pole of the solencid. Place an *N* and *8 directly on the diagram. I mark b) Determine the new strength of the magnetic field if the following parameters are changed: i. The student adds three times as many turns of wire to the solenoid, while the length and current stay the same. I mark ii. The current and turns are kept the same but the coils are spread out so that the solenoid is 1.5 times longer. I mark . The current and length is doubled, with 1/4 as many turns in the solenoid. 11l 2 marks Page 3 of 10