Final answer:
A radiation dosimeter is used to test the accuracy of the x-ray timer by measuring the exposure to ionizing radiation, thereby ensuring the proper function and safety of x-ray equipment.
Step-by-step explanation:
The device used to test the accuracy of the x-ray timer is known as a radiation dosimeter. Dosimeters are instruments that measure the exposure to ionizing radiation. They are commonly utilized in environments where radiation is used, such as in medical settings to monitor x-ray equipment. A dosimeter can detect the amount of radiation by the discharge of a rechargeable internal capacitor, and the amount of discharge is directly related to the amount of ionizing radiation encountered. This measurement is essential for ensuring that x-ray machines are operating properly and safely, delivering the correct dosage of radiation.