How many identical lamps must be connected in series in the manufacture of a Christmas tree garland for a voltage of 220 V

| September 7, 2021 | education

How many identical lamps must be connected in series in the manufacture of a Christmas tree garland for a voltage of 220 V, if the resistance of each light bulb is 64 Ohms, and the current strength in it should be 0.2 A.

The bulbs in the Christmas tree garland are connected in series and the current strength in any part of the garland is the same, and the voltage is equal to the sum of the voltages of all connected bulbs.
N = U / u, where U is the mains voltage (U = 220 V), u is the nominal voltage of one bulb.
u = I * R, where I is the current strength (I = 0.2 A), R is the resistance of one light bulb (R = 64 ohms).
N = U / u = U / (I * R) = 220 / (0.2 * 64) = 17.1875 ≈ 18 bulbs (since the current in the bulb should not exceed the permissible value).
Answer: You need to connect 18 bulbs.



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