People cannot see, taste or smell ionising radiation. Most of its effects cannot be observed by eye. Radiation can only be detected using specialised monitoring equipment. With the correct equipment, it is usually easy for a trained person to identify radioactive objects.
Geiger-muller counter radiation detector
© Birmingham Museums Trust
Welsbach type C burner and incandescent mantle made of thorium
© The Board of Trustees of the Science Museum
Harwood self-winding wrist-watch with radium painted numbers and hands c.1930
© The Board of Trustees of the Science Museum
Electron capture detector containing a nickel-63 source, c.1960
© The Board of Trustees of the Science Museum
Uranium glass bowl under UV light
© Sharon Robinson-Calver
L85A2 rifle with a gun sight containing tritium gas
© Imperial War Museum
Cockpit instrument panel of a Heinkel He 111 with radium painted dials
© Imperial War Museum