Purpose
This interactive allows you to explore the formation of images using mirrors and lenses.

Using the Interactive

• Configure the interactive using the PLACE OBJECT and BEAM CONTROL templates on the right-hand side.
• The interactive consists of an "optical bench" (the white area) onto which you can place mirrors, lenses, and objects.
• The optical bench sits in a coordinate system to set and check precise values. The upper left corner is the origin. The position of an object is given under it.
• The central black line is the principal axis for all optical elements.

• PLACE OBJECT: This section lists the elements that may be placed onto the bench. Select an element from the list, then click on the bench at the desired location for the element.
• Click an element to see its location.
• Light Beams: This section allows for 0 to 8 beams to be displayed, followed by a list of possible colors.
• Ray Diagram: When an object is placed on the bench, this option draws an accurate ray diagram.
• Virtual Rays: If the image in a ray diagram is virtual, use this checkbox to display the virtual rays.
• Remove Object: To remove an object from the bench, click the Delete button under the object.
• The focal length of objects can be controlled by dragging the focal point.
• The heights of objects can be controlled by dragging the arrows at the top of the object.

1			Select a CONVEX LENS and place it approximately in the center of the bench (near x = 300). Note the focal length and the position of the lens listed beneath it. What will happen if you send several beams, all parallel to the principle axis, through the lens?
			A)	They will all reflect off the lens.
			B)	They will pass through the lens and scatter.
			C)	They will pass through the lens and focus on a single point.
			D)	They will pass through the lens and remain parallel.
2			Select 2 BEAMS from the menu. Deselect BLUE How will the picture change if you increase the focal length of the lens?
			A)	It will not change at all.
			B)	The rays will focus on a point farther from the lens.
			C)	The rays will focus on a point nearer to the lens.
3			Set the focal length back to 50. Select RAY DIAGRAM. If you place an object a distance greater than 50 units from the lens, what kind of image will you get?
			A)	real and upright.
			B)	real and inverted.
			C)	virtual and upright.
			D)	virtual and inverted.
4			Select COMPLEX OBJECT. Place it near x = 200. If you place the object a distance less than 50 units from the lens and its size and that of the lens are such that both rays intersect the lens, what kind of image will you get? [Note: the object must be small enough and the lens big enough for both rays to intersect the lens for the virtual image to be visible.]
			A)	real and upright.
			B)	real and inverted.
			C)	virtual and upright.
			D)	virtual and inverted.