Meaning and mechanism
When current flows through a resistor, electrical energy is converted into internal energy. Power is the rate of this conversion, and heat is the amount of energy transferred over time.
The fuse is a component that heats up due to excessive current and breaks the circuit. After it breaks, the closed path disappears, thereby stopping further current and heat generation due to resistance.
Relationships and conditions
P=I²R, and under constant conditions Q=Pt. At fixed voltage, P=V²/R, so a larger resistance does not necessarily mean greater heating power.
The simulation calculates temperature rise from heat capacity, omitting cooling and temperature-dependent resistance. A real fuse’s behavior depends on its current–time characteristics.
What to observe in the simulation
P = I²R; after the fuse opens, current and additional heating are zero.
The 0.5 s fuse delay is an educational approximation. Cooling, temperature-dependent resistance and fire are not simulated. Experiment on screen; do not reproduce this with real power supplies, outlets or high voltage.
Key relationships and symbols
P = I²R · Q = Pt · T = 20 + Q/Cth
| Symbol | Meaning | Unit |
|---|---|---|
| P | Heating power | W |
| Q | Heat transferred | J |
| Cth | Heat capacity of the object | J/K |
Worked example
Under the same conditions, what is the total heat at 10 s if the fuse blows after 0.5 s?
1.8 J
Common misconceptions
- Power, measured in W, and the amount of heat generated over a period of time, measured in J, are not the same physical quantity.