Question

light brightness

1. you need to adjust the brightness of the light depending on the objective that you use. see table 2.1.
2. when you have a lower power objective in place (such as the 4× objective), will you need more or less light? ____________

light intensity
the diaphragm changes the intensity of the light reaching the slide. adjusting this control can give you a sharper image of the specimen.

1. why do you need to adjust the diaphragm? __________________________

adjusting focus
the adjustments knobs are used for focusing. the coarse adjustment knob moves the stage up or down for major focusing changes and is used primarily with the 4× and 10× objectives. the fine adjustment knob moves the stage slightly up or down for minor focusing changes that sharpen the image. when at higher magnifications, you only use this knob so that you don’t acci - dentally push the objective into the slide.

1. which adjustment knob would you use when using the 4× objective? ____________
2. which adjustment knob would you use when using the 10× objective? ____________
3. which adjustment knob would you use when using the 40× objective? ____________
4. which adjustment knob would you use when using the 100× objective? ____________

a. why must you never use the coarse focus knob with the 40× or 100× objectives? ____________

Explanation:

1. Lower - power objectives require less light as they gather more ambient light.
2. Adjusting the diaphragm controls light intensity to get a sharper specimen image.

3 - 4. For 4x and 10x objectives, the coarse adjustment knob is used for major focusing changes. For 40x and 100x objectives, only the fine adjustment knob is used to avoid pushing the objective into the slide. Using the coarse knob at high magnifications can damage the slide and objective.

Answer:

1. Less light
2. To control light intensity for a sharper specimen image
3. Coarse adjustment knob
4. Coarse adjustment knob
5. Fine adjustment knob
6. Fine adjustment knob

a. To avoid pushing the objective into the slide and causing damage to the slide and objective.