The lamp in your projector or overhead projector projects an image onto a medium using optimal quality.
Have you noticed recently that the image quality is bad, the colour is wrong or there's a problem with the brightness and contrast? It is probably the lamp that is at fault.
If no image appears at all, it is very likely down to the lamp being defective.
Want to change the blown bulb in your projector? Order the right part for your appliance here. Large number of models available.