Effects of Electric Current — Maharashtra (SSC) Class 10 Science Solutions (Free)

Electric current is the flow of electric charge per unit time. Unit: Ampere (A). Current = charge/time = Q/t. Ohm's law: V = IR, where V is potential difference, I is current, R is resistance. At constant temperature, current through conductor is directly proportional to applied potential difference. Limitations: Does not apply to non-ohmic conductors (semiconductors, gases at low pressure), at very high temperatures, or to some nonlinear devices like diodes and transistors.

Step 1: Given R = 10 ohm, I = 2 A Step 2: Use Ohm's law: V = IR Step 3: V = 2 x 10 = 20 V Answer: Potential difference is 20 V. This means 20 joules of energy is given to each coulomb of charge passing through the wire.

Heating effect: When current flows through a conductor, it generates heat due to friction between moving electrons and atoms. Formula: Heat = I2Rt (Joule's law of heating). Factors: (1) Current (I): Heat is proportional to square of current, (2) Resistance (R): Heat is directly proportional to resistance, (3) Time (t): Heat is proportional to time of flow. Higher current, higher resistance, or longer duration produces more heat. Used in heaters, bulbs, electric stoves.

Step 1: Given I = 5 A, R = 20 ohm, t = 10 s Step 2: Use Joule's law: H = I2Rt Step 3: H = (5)2 x 20 x 10 Step 4: H = 25 x 20 x 10 = 5000 J Answer: Heat produced is 5000 joules or 5 kJ. This heat warms the conductor and surroundings.

Magnetic effect: When current flows through a conductor, a magnetic field is produced around it. Direction: Given by right-hand rule (thumb in current direction, fingers curl in field direction). Strength increases with current. Uses: (1) Electromagnets in electric bells, door locks, relays, (2) Magnetic field in electric motors, (3) Solenoids in switches. Current-carrying coil acts like a magnet. Strength can be controlled by changing current.

Power: Rate of energy consumption or transfer. Formula: P = VI = I2R = V2/R. Unit: Watt (W). Energy: Work done by electric current. Formula: E = Pt = VIt. Unit: Joule (J) or kWh. Calculation: P = VI = 10 x 5 = 50 W. This means 50 joules of energy is dissipated per second. In 1 hour, energy = 50 x 3600 = 180000 J = 0.05 kWh.

Heating effect: (1) Electric heater/geyser, (2) Incandescent bulb (filament glows), (3) Electric stove/cooker, (4) Toaster. Magnetic effect: (1) Electric bell (electromagnet attracts armature), (2) Electric motor (coil rotates in magnetic field), (3) Relay (electromagnet controls switch), (4) Solenoid (creates magnetic field). Some devices use both effects, like microwave (magnetic field generation plus heating).