Ph272a- General Physics II (Electricity and Magnetism) Quantitatives: Capacitor, Capacitance, Energy Stored 1. Calculate Capaci

Ph272A- General Physics II (Electricity and Magnetism) Quantitatives: Capacitor, capacitance, energy stored 1. Calculate capacitance, charge stored, energy stored (a) A parallel-plate capacitor filled with mica between the two plates. The plate is 10 cm x 10 cm. The plates are separated by 2 mm. The dielectric constant of mica is 5.4 and dielectric strength is 160 kV/mm. Find the capacitance, the maximum charge it can hold without suffering dielectric breakdown, the maximum energy stored. (b)) A “spherical” capacitor consists of two concentric conducting,, spherical shells with inner radius a=10 cm and outer radius b=10.2 cm. The space between two shells is filled with mica. Find an approximate value for the capacitance. 2. How the electric field and energy stored are affected by dielectric? We will compare two capacitors of the same dimensions, one with a dielectric (such as mica) and one without (vacuum). We put the same amount of charge on both capacitors (say 1 nC). We will compare the voltage, the electric field and the energy stored for these two capacitors. Use the same dimensions for the capacitors as in Q.1 a. 3. Capacitor circuits (a) Parallel circuit- Two capacitors, C1 =10µF,C2 = 5µF are in parallel and are connected to a 20-volt battery. Find the charge stored and potential across each capacitor after they are fully charged. What is the equivalent capacitance? € (b) Series circuit - Two capacitors, C1 =10µF,C2 = 5µF are in series and are connected to a 20- volt battery. Find the charge stored and potential across each capacitor after they are fully charged. What is the equivalent capacitance? (For series circuit, you need to find the equivalent capacitance first.) € 4. Challenging problem. Refer to the capacitor in Q.1(a). Suppose only half of the space between the plates is filled with mica the other half is filled with air (dielectric constant = 1.00059 ~ 1, dielectric strength = 3 kV/mm). (a) Find the capacitance. (b) Find the the maximum charge it can hold without suffering dielectric breakdown..

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