A 10μ F capacitor is connected in series with a 0.7 MΩresistor across a 200 V d.c. supply. If the p.d. across the capacitor continued increasing at the initial rate, it would be represented by OA, the tangent drawn to the initial part of the curve. If T is the time constant in seconds, namely the time required for the p.d. across C to increase from zero to its final value if it continued increasing at its initial rate. This result is really obvious from the fact that at the instant of switching on there is no charge on C and therefore no p.d. across it. Consequently the whole of the applied voltage must momentarily be absorbed by R. (a) Find the time constant and the initial charging current. (b) Calculate the time taken for the p.d. across the capacitor to grow to 150 V. (c) Calculate the current and the p.d. across the capacitor 7.0 s after it is connected to the supply
A 10μ F capacitor is connected in series with a 0.7 MΩresistor across a 200 V d.c. supply. If the p.d. across the capacitor continued increasing at the initial rate, it would be represented by OA, the tangent drawn to the initial part of the curve. If T is the time constant in seconds, namely the time required for the p.d. across C to increase from zero to its final value if it continued increasing at its initial rate. This result is really obvious from the fact that at the instant of switching on there is no charge on C and therefore no p.d. across it. Consequently the whole of the applied voltage must momentarily be absorbed by R.
(c) Calculate the current and the p.d. across the capacitor 7.0 s after it is connected to the supply.
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