Why wires fight current

Science · Energy · ages 16-17

Name ______________________ Date ____________

Run doubles at same cut. What befalls drag?
- It halves
- It doubles
- It stays
What ties drag, run, cut, and stuff mark?
- R as rho L by A
- R as L plus A
- R as rho plus L
Copper fits links since its mark runs low.
Circle one: True False
A wire folds to half run and twin cut. What befalls drag?
- It quarters
- It doubles
- It stays
A 4 ohm wire is drawn to twice its run at same cut. What is the new drag in ohms?
Answer: ______________
Drag 2 ohms, cut 1 square, run 4 long. What is rho?
Answer: ______________
Run trebles at same cut from 3 ohms. What is the new drag in ohms?
Answer: ______________
Fires need glow, links need thrift. Which pairing fits?
- Nichrome links, copper fires
- Copper fires, nichrome links
- High-mark fires, low-mark links

Answer key

For grown-ups. Fold this page away before handing over the rest.

It doubles · Twice the run means twice the drag.
R as rho L by A · Mark times run split by cut gives drag.
True · Low-mark stuff wastes scant power.
It quarters · Half run times twin cut means a fourth.
8 · Twice the run at same cut means twice the drag.
0.5 · Rho as R A by L: 2 times 1 split by 4.
9 · Three times the run means three times the drag.
High-mark fires, low-mark links · High marks turn flow to heat; low marks spare it.