The following examples use the Orders table to show how the positive and negative unary operators function. When a positive unary operator is set against a negative value, the returned value is negative (positive_value * negative_value = negative_value). When a negative unary operator is set against a negative value, the returned value is positive (negative_value * negative_value = positive_value). Copy. SELECT (DATEPART(day, Order Date) - DATEPART(day, Shipped Date)) FROM Orders WHERE OrderID = '10248' -- Without a unary operator, the value returned is '-12'.
Inmersion oil does not increase magnification. Inmersion oil is needed at high magnifications. Why? High magnifications come with high numerical appertures (although one can have a low-magnification high-numerical apperture objective). High numerical appertures are required to capture more light and improve resolution.
Before using immersion oil, make sure that your 100x objective lens is made for use with immersion oil. 1  Begin by focusing your sample using the 40x objective lens. Rotate the objective lens part way between the 40x and 100x lens so you can reach the cover slip on your slide.