Related Clues:

• Candle relative
• Light bulb measure
• See 17 Across
• Solar panel unit
• Bulb measure
• A light amount?
• Light emission unit
• *Measure of brightness
• Light measure
• One joule/second
• Inventor
• Eponymous Scottish inventor
• Measure of light
• Light unit
• It might ask 'What comes next?'