Current Electricity: common misconceptions

If your child says… “Current goes the same way as electrons.”

Ask together

Which current direction matches negative charges moving left?

What’s true

Electrons carry negative charge, so conventional current points opposite to their movement.

If your child says… “The longer wire has greater resistivity.”

Ask together

Does making this wire longer change its material or temperature?

What’s true

Changing wire dimensions changes resistance, while resistivity stays unchanged at the same temperature.

If your child says… “A stronger field increases electron mobility.”

Ask together

If drift speed and field both double, does their ratio change?

What’s true

At fixed temperature, drift speed rises with field, but mobility stays constant in an ohmic metal.

If your child says… “Warmer electrons move faster, so metal conducts better.”

Ask together

Which way does the metal's resistance curve go as temperature rises?

What’s true

In a heated metal, increased scattering hinders drift despite faster random electron motion.

If your child says… “My heater always uses its rated power.”

Ask together

Would the same resistor still draw 2 amperes if its voltage were halved?

What’s true

With resistance unchanged, half the rated voltage gives one quarter of the rated power.

If your child says… “Every cell adds its emf, whichever way it faces.”

Ask together

Would turning the cell around change which way it drives charge?

What’s true

In series, a reversed cell's emf subtracts, but its internal resistance still adds.

If your child says… “Currents meeting at right angles add like arrow lengths.”

Ask together

Would turning either resistor branch change the charge arriving at the junction?

What’s true

Charge entering a steady junction must leave it, regardless of wire angles.

If your child says… “A balanced bridge has no current anywhere.”

Ask together

What voltage difference remains across each complete outer path?

What’s true

Balance removes detector current, while both resistive paths remain across the supply.