- control rotor
- control time
- controller
- conversion gain
- conversion kit
- converter station
- conveying belt
- cooling tower
- core diameter
- core loss
- core plate
- core saturation
- core test
- core transformer
- cored carbon
- cored solder
- coreless armature
- corner iron
- corona
- corona discharge
- corona effect
- corona stabilization
- corona tube
- corporation
- correction
- corrector
- corrector circuit
- corrugated tank
- cosphi meter
- cotton braid
- cotton covered
- coulombmeter
- counter-cell
- counterpoise earthing
- couple
- coupled circuits
- coupling circuit
- coupling resistor
- covering cover
- coulometer
- counter oil
- countercurrent
- coupled surge
- coupler connector
- coupling
- coupling coil
- coupling impedance
- coupling loop
- coupling resistance
- coupling transformer
- cradle dynamo
- create
- creep
- creepage distance
- creeping discharge
- crimped connection
- critical defect
- critical error
- critical field
- critical load
- crystal cartridge
- crystal detector
- crystal oscillator
- crop compensation
- cross-connect
- crossbar selector
- crossover point
- Cruie principle
- crystal set
- cubic
- cubicle
- cupreous
- Curie point
- currency
- current
- current amplification
- current bias
- current circuit
- current coil
- current control
- current density
- current direction
- current distribution
- current divider
- current drop
- current feedback
- current fluctuation
- current generator
- current impulse
- current lead
- current limiter
- current limiting
- current output
- current path
- current peak
- current potential
- current pulse
- current pulsing
- current range
- current ratio