Simulation · Physics · Class 12
Two bulbs on the mains
From the lesson Electrical energy and power in Current Electricity. Change the values and watch what happens.
Two bulbs on the mainsPhysics · Class 12
The idea behind it
NCERT § "Electrical Energy, Power"
- When charge moves through a potential difference V, the energy transferred per unit time is P = VI.
- For a resistor, the power dissipated as heat is P = I²R = V²/R (Joule heating).
- Two appliances rated for the same voltage: the one with the higher power rating has the lower resistance, since R = V²/P.
- In series, the same current flows, so the higher-resistance device dissipates more power; a lower-rated bulb glows brighter when connected in series with a higher-rated one.
- In parallel, the same voltage is applied, so the lower-resistance device dissipates more power.
- Power is sent over long distances at high voltage: for a fixed power P delivered through cables of resistance R_c, the loss P²R_c/V² falls sharply as V is raised.
- The kilowatt hour is the commercial unit of electrical energy, 1 kWh = 3.6 × 10⁶ J.