Switch in a Circuit

• A switch controls whether a circuit is open or closed.
• To connect a switch in series with a bulb and cell — ON closes, OFF opens.
• Everyday switches at home linked to the same principle (always use cells in lab, not mains).
• How switches improve safety and convenience in torches, fans, and room lights.

Level 1 — Open and closed switch

Verbal: A switch is a device that makes or breaks the conducting path in a circuit.

Symbolic: ON → switch closed (metal contact touches) → current flows → bulb glows.

Visual:

Construction (simple lab switch): Two metal strips; pressing brings them together — homemade switch from safety pin and drawing pin (NCERT activity).

Level 2 — Series placement and real applications

Correct placement: Switch in series with bulb — turning OFF breaks the whole path.

Torch: Cell → switch → bulb → back — switch saves battery when not needed.

Multiple bulbs: One switch can control several bulbs if wired in series (all on/off together).

Safety: Switch before appliance in household wiring (conceptual) — cutting supply prevents shock during repair (advanced; Class 6 focuses on cell circuits).

Circuit diagram: Switch shown as gap line that closes when ON.

Design a circuit: one cell, one bulb, one switch — bulb should glow only when switch is ON.

Step 1 — Connect cell (+) to switch terminal 1
Step 2 — Switch terminal 2 to bulb terminal 1
Step 3 — Bulb terminal 2 back to cell (−)
Step 4 — Press switch ON → closed loop → bulb glows
Step 5 — Switch OFF → open at switch → current stops → bulb off

• What does a switch do in an electric circuit?
• Difference between switch ON and switch OFF in terms of current?
• Why is a switch placed in series with a bulb in a torch?
• Sketch a circuit diagram with cell, bulb, and switch (OFF position).

Open the Practice tab for graded questions on Switch in a Circuit.