Q. The approximate radiographic equivalence factors for steel and copper at 220 kV are 1.0 and 1.4 respectively. If it is desirable to radiograph a 1.27 cm (0.5 inch) piece of copper, what thickness of steel would require about the same exposure characteristics?

• (A) 1.78 cm (0.7 inches)
• (B) 0.9 cm (0.35 inches)
• (C) 3.55 cm (1.4 inches)
• (D) 2.54 cm (1.0 inch)