Electromagnetic spectrum — practice question

What is the approximate wavelength range in free space for infrared radiation?

• A$100\ \text{nm}$ to $400\ \text{nm}$
• B$300\ \mu\text{m}$ to $30\ \text{cm}$
• C$400\ \text{nm}$ to $700\ \text{nm}$
• D$800\ \text{nm}$ to $1000\ \mu\text{m}$