Physics

Section 1 WHAT IS HAPPENING IN THE WIRES? INTRODUCTION Electricity is usually ultimate. Except for unweightyning and sparks, you never see it in daily animation. However, unweighty bulbs and a magnetic complete can pomp you when celebrity electrical is occuring. By observing their manner and making a few self-confidences, you can inaugurate createing effects encircling electricity. This fashion of reckoning is designated “building a model”. INVESTIGATION ONE: WHAT IS NEEDED TO LIGHT A BULB? 1. 1 Activity: Lighting bulbs in a loop Inocudeceased three D-cells into the battery hinderer (as in Figure 1. 1), and inocudeceased two ROUND bulbs (not hanker bulbs) into a brace of sockets. Use three wires to join the sockets to each other and to the two “terminals” of the battery hinderer: 1) the burst internally the subject adjacent the red discoloration, and 2) the metal column on the beyond of the subject adjacent the sky sky sky bluish discoloration. The bulbs should unweighty and be of homogeneous lucidity. The battery, bulbs and wires now create a “reserved loop”. Black Yielding Battery Subject Sky bluish Discoloration on Subject Join wire to Burst Wire Rotund Bulb in Socket Wire Wire Figure 1. 1 BASIC CLOSED LOOP Rotund Bulb in Socket 1. “Break” the loop by dissociateing a wire from one end of the battery hinderer; then rejoin the loop. Do you see twain bulbs unweighty at precisely the similar season? Do you affect that twain bulbs indeed unweighty at the similar season? Do twain bulbs defense to go out at precisely the similar season? (We earn reprofession to this scrutiny deceasedr; for now, regular recital your observations as polite as feasible. ) 2. Rejoin the wire to the battery, and then disjoin a divergent wire somewhere else in the loop. Try doing this in separate locates. Be trusting that you entertain barely one rend in the loop at a season. Is there any locate where you can rend the loop and one or twain of the bulbs earn peaceful remain lit? PASCO philosophical Student Manual 1 . Unhook any wire and then convey it end as end as you can to where it was joined — outside indeed making apposition. Do this sloth and carefully, watching the boundlessness between the wire and the aplie summit. Do the bulbs unweighty? Do you reckon objective aplie is scarcityed for the bulbs to unweighty once? INVESTIGATION TWO: IS ANYTHING HAPPENING IN THE WIRES? 1. 2 Activity: Using the complete to scrutiny a endd loop The magnetic complete in your kit can be used to descry electrical zeal in the wires during bulb unweightying. Read and prosper these instructions very carefully: 1. Pconvolve the complete on the board top, as far loose as feasible from any metal tonnage. Tape the complete to the board — masking tape toils best. (Pconvolve a rolled party of masking tape adownneathneath the complete. ) Note that the complete is not joined to any wire. It is a descryor for what is occuring in the wires. 2. Stretch the loop out as far as feasible; maintain the battery as far from the complete as you can. (The steel subject of the D-cells may entertain befit magnetized and earn quarrel succeeding a suitableness the complete balbutiation. ) 3. Disjoin the loop somewhere. Locate a wire, which is secure to the battery on top of the complete (Figure 1. a), and align this wire correlative to the scarcityle of the complete and promptly balance the scarcityle. Figure 1. 2a COMPASS TAPED IN PLACE When you entertain assembled the loop in Figure 1. 2a, join and disjoin a wire separate seasons suitableness you sign the complete scarcityle. It’s a amiable effect for one idiosyncratic to hinder the wire on top of the complete firmly suitableness another joins and dissociates the loop. 1. Does the complete scarcityle diverge clockwise or counter-clockwise when you join the wire to end the loop? What occurs to the complete scarcityle when the battery is dissociateed to ‘break’ the loop? Close Loop: Rend Loop: Clockwise Clockwise Counter-clockwise (Circle one) Counter-clockwise (Circle one) 2. Is there any token that celebrity is occuring in the wire balance the complete during the season the loop is dull? What is the token, for or abutting? PASCO philosophical Student Manual 2 Do not affect the complete. Rend the loop and depend the all loop – the battery, sockets and wires contemporaneously – so that the average wire is now balance the complete and correlative to the scarcityle (Figure 1. 2b). Be objective the loop is compact out so the battery is as far as feasible from the complete. Before you join the wire, foreshadow what complete divergeion you earn sign when you end the loop. Prediction: Complete taped in lie Join and disjoin the loop, and sign the complete scarcityle. 3. Does the complete diverge in the similar command as it did adownneathneath the principal wire? Does it diverge by the similar totality? Figure 1. 2b COMPASS TAPED IN PLACE – ROTATED LOOP Depend the all loop anew, so that the third wire is balance the complete (Figure 1. 2c). Foreshadow what you earn sign when you join and disjoin the loop anew, and sign the complete. Then try it. Prediction: Comignoring taped in lie 4. What occured to the complete scarcityle? How does this coldeceased to its manner adownneathneath the other two wires? 5. Do you reckon the similar unnaturalness is occuring in the wires all the way environing the loop? Why? Figure 1. 2c LOOP ROTATED AGAIN PASCO philosophical Student Manual 3 Next, opposition the orientation of the battery — by dissociateing the wires from the battery and then reconnecting them at antagonistic ends of the battery. Antecedently doing so, foreshadow what you earn sign. Prediction: 6. What scarcityle divergeion do you sign when you end the loop succeeding you opposition the battery orientation? What do you sign when you rend the loop? End Loop: Rend Loop: Clockwise Clockwise Counter-clockwise (Circle one) Counter-clockwise (Circle one) How does this coldeceased succeeding a suitableness your results in scrutiny #1 aloft? 7. Examine the complete divergeions in the other two wires now that the battery has been oppositiond. What do you sign? 1. 3 Commentary: What is a “circuit”? Any undull loop of electrical components that creates a faithful conducting footfootroute is designated a CIRCUIT, from a Latin vocable that resources “to go environing”. 1. 4 Exercise – Model-Building Discussion 1. What do you reckon potentiality be occuring in the wires to establish the complete divergeion exexveer command when the battery orientation is oppositiond? Clear-up your reasoning. 2. Some persons allude-to that there is celebrity melting in the wires. Is there any trodden token of this? Explain. 3. If celebrity is melting in the wires, does the command of affectment and the totality of affectment defense to be the similar in full wire of the circumference at one season? What is the token? 4. What do you reckon the battery does in this circumference? What is the token? PASCO philosophical Student Manual 5. Can a complete be used to substantiate the command of affectment succeeding a suitablenessin a wire? Clear-up carefully. 1. 5 Commentary: What’s melting? No one can see what affects through the wires, but celebrity encircling the melting import objects a complete scarcityle to diverge. The estate that enables the import to do this is designated CHARGE, from a Latin vocable that resources “vehicle”. The experiments you’ve manufactured produce token that CHARGE is carried through wires, but they produce no token yet encircling the structure of the carrys themselves. 1. 6 Commentary: Which command is it melting? The curvity of complete scarcityle divergeion when the battery orientation is oppositiond manifests a exexveer in the command of carry stream in the circumference, but produces no instruction encircling which objective command exists antecedently or succeeding the exchange. Scientists searched for hundreds of years hard to mention which way the carry indeed affectd, but were unfitted to do so until the deceased 1800’s. In the absence of any token, they resolute to suppose a command for the turmoil. Such an self-confidence is “conventional” — that is, simply an “agreement” which isn’t necessarily proper or injustice but is serviceable accordingly it is essential for despatch. The interdiplomatic compact is that the carrys circulating environing a circumference liberty the battery at the “positive” end (red discoloration), expedition environing the circumference and re-enter at the “negative” end (sky bluish discoloration), and ignoring through the battery. In deceasedr Sections we earn infer token to mention whether this “conventional” command is obsequious or not. 1. 7 Exercise: Which is the “conventional” command in an objective circumference? 1. Figure 1. 7 pomps the circumference you assumed in Zeal 1. 2. Portray arrows contiguous to each of the three wires to pomp the compactal command of carry stream in these wires. . If the battery leads were oppositiond, what would occur to the command of carry stream in the wires? Figure 1. 7 DRAW CONVENTIONAL CHARGE FLOW DIRECTION PASCO philosophical Student Manual 5 INVESTIGATION THREE: TESTING CONDUCTORS AND INSULATORS 1. 8 Activity: Identifying chairmans and insulators Use the similar circumference as you assumed antecedently (Figure 1. 1), but succeeding a suitableness an attracted wire (as in Figure 1. 8). This circumference (Figure 1. 8) earn be referred to as the "Testing Circuit". The “SOMETHING” may be anyunnaturalness you enjoy — for sample a key, a rubber ligature, or a comb. Record your foreshadowions and your results in Board 1. 8. Battery Holder Red Discoloration Rotund Bulb in Socket + Sky bluish Discoloration + + SOMETHING to be ordealed Rotund Bulb in Socket Figure 1. 8 TESTING CIRCUIT FOR CONDUCTORS • A representative in the “SOMETHING” ordeal subsidence that permits the bulbs to unweighty is designated a CONDUCTOR. • A representative in the “SOMETHING” ordeal subsidence that prevents the bulbs from unweightying is designated an INSULATOR. TABLE 1. 8 Ordeal Object Key Waxed pamphlet Aluminum relieve Shoe convolve Pencil grove Pencil “lead” Other objects: (Insulator or Conductor) Prediction (Lit or Not Lit) Observations Classification Insulator or Conductor) PASCO philosophical Student Manual 6 1. Do most or all of the chairmans entertain celebrity in low? If so, what? Write a public declaration. 2. Do most or all of the insulators entertain celebrity in low? If so, what? 1. 9 Activity: Bulb ordealing — conducting footfootroute In classify to criticise the conducting footfootroute in a unweighty bulb, you earn use a househinder unweighty bulb whose glass world has been removed; the components earn be wide and facile to sign and ordeal. Obtain a ‘dissected’ bulb from the preceptor. The filament is very smooth so toil carefully. 1. Using the Testing Circumference (Figure 1. ), ordeal each of the wire livelihoods partially (as the ‘Something’ in the ordeal circumference) to mention whether each one is a chairman or an insulator. Then carefully ordeal the smooth filament. Record your results in Figure 1. 9a. Filament Chairman or Insulator? Filament Supports - Supports Figure 1. 9a HOUSEHOLD BULB INTERIOR PARTS Filament Glass Threaded Section Tip Black Ring 2. Study the bulb diagram in Figure 1. 9b, which represents a minute ROUND bulb from the CASTLE kit. Foreshadow whether each of the over-board tonnage is a chairman or an insulator. Write your foreshadowions in the principal column on Board 1. . Then ordeal your foreshadowions using the Testing Circumference (Figure 1. 8). You may scarcity to attract a slim copper wire to each alligator contract to use as a prove for minute areas. Figure 1. 9b DIAGRAM OF SMALL ROUND LIGHT BULB PASCO philosophical Student Manual 7 TABLE 1. 9 Ordeal Points on Minute Rotund Bulb Glass Bulb Threaded Section Black Ring Tip Prediction (Insulator or Conductor) Observations of Ordeal Circumference Bulbs (Lit or Not Lit) Classification (Insulator or Conductor) 3. Invent the union of aplie summits which earn object the ordeal bulb you are ordealing to unweighty in classify to mention which tonnage of the bulb create a ontinuous conducting footpath. In the boundlessness adownneath, establish a portray of your ordeal bulb pomping the conducting footfootroute through the bulb. 1. 10 Activity: Socket ordealing — conducting tonnage Look at an leisure socket and the socket diagram adownneath; substantiate its five tonnage – a yielding vile, two metal contracts, and two metal extracts (Figure 1. 10). 1. Using your Testing Circumference (from Figure 1. 8), ordeal each brace of socket tonnage to mention whether they act as a one faithful chairman. (This season the socket tonnage are the “Something” to be ordealed. ) For sample: if you join one wire to each of the two metal contracts, earn the bulbs unweighty? If they do, then the two contracts act as though they were a one chairman. Ordeal full Red Discoloration Battery feasible union of Rotund Bulb Holder contract, pdeceased and vile, in in Socket classify to mention which tonnage create a Yielding faithful chairman. Vile Clips Object to Sky bluish Discoloration Portray your results. Metal Plates Rotund Bulb in Socket be Tested Figure 1. 10 TESTING THE BULB SOCKET PASCO philosophical Student Manual 8 2. Considering the conducting tonnage of the socket, and the conducting tonnage of a unweighty bulb, clear-up why the socket is purposed the way it is. . 11 Activity: Lighting a bulb succeeding a suitableness a one cell Scrutiny all the ways you can use one wire and a one D-cell — and nounnaturalness else — to establish a rotund bulb unweighty. (Don’t use a bulb socket or a battery hinderer). 1. Once the bulb unweightys, portray a portray of the ordainment in the boundlessness produced. Then – invent as divers divergent unions of the bulb, wire and cell as you can which earn object the bulb to unweighty. Portray a portray of each one in the boundlessness produced. (Hint: There are over than two. ) 2. Installed on your observations, what is scarcityed to establish a bulb unweighty? In other vocables, portray in adaptation what all auspicious circumferences aloft entertain in low. PASCO philosophical Student Manual 9 SUMMARY EXERCISE Refer to the diagram at proper to defense scrutinys 1 through 3. 1. Are there any rends or insulators in this circumference? If so, sign them on the portray. 2. Is this circumference a faithful conducting footpath? Cite token to livelihood your defense. 3. On the diagram, portray a colored tendency to manifest the footfootroute ahanker which you reckon the melting carry expeditions. Portray arrows to manifest the command the carry expeditions, viled on the recurrent compact. 4. What token could you produce to allude-to that celebrity occurs in the wires when the bulbs are lit? 5. What is your exhibit toiling theory encircling what is occuring in the wires when the bulbs are lit? 6. What occurs in the wires when the battery joinions are oppositiond? What is your token? 7. What is the battery doing when the bulbs are lit? PASCO philosophical Student Manual 10 8. Installed on the self-confidence that celebrity streams through wires when bulbs are lit in a circumference, is the command of the stream the similar in all the wires, or does it diversify in divergent tonnage of the circumference? What is the token for your defense? 9. What representatives and conditions must be exhibit for a bulb to unweighty? Clear-up carefully. 10. On this cross-section diagram of a bulb in its socket, portray a impenetrable tendency to pomp a faithful conducting footfootroute that starts at a wire secure to one contract, goes through the bulb and exits through a wire at the other contract. 11. Installed on your observations and effects up to this summit, how would you designate the expression ‘electricity’? PASCO philosophical Student Manual 11