Question

Tutorial 9: Electricity I (week 10) 1) A typical thunderstorm can be regarded as comprising two charges of +40 C and -40 C, separated in air by a distance of 5 km Calculate the magnitude of the force between the charges 2) Four charges are arranged at the corners of a square with sides length, L, as shown Q: 4 mC, q = 2 mC and L = 10 cm a) Find the magnitude of the .Q net force on q What is the electric field at this point? b) -a 4Q 3) In a certain linear accelerator, electrons are emitted from an electron gun into a standing wave accelerator tube that is 0.8 m long. At the end of the tube is an accelerating anode carrying a potential of 20.0 MV a) Find the speed of an electron when it reaches the end of the tube where it strikes a tungsten target b) Is this result realistic? 4) A parallel plate capacitor in a radio comprises two strips of aluminium foil with a plate area of 0.75 m2, separated by a polyethylene dielectric 2 x 105 m thick, (E-2.6). A potential difference of 30 V is applied. Find a) the capacitance b) the charge on each plate c) the electric field in the dielectric d) the stored potential energy

Answer 1

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